How do red blood cells know when to die?

The impact of everolimus on hematologic parameters in patients with renal angiomyolipoma associated with tuberous sclerosis complex

BACKGROUND

Everolimus is an effective treatment for renal angiomyolipoma associated with TSC (TSC-RAML). However, its impact on hematologic parameters in TSC-RAML patients remains unclear.

METHODS

Hematologic data were collected from TSC-RAML patients undergoing everolimus treatment in two registered clinical trials. Dynamic changes in hematologic parameters during treatment were analyzed. Additionally, we also explored variations in hematologic impact based on gender and age within the patient population.

RESULT

A total of 55 patients from the two clinical trials are included in this analysis. Hemoglobin, white blood cells (WBC), lymphocytes, neutrophils, and platelet showed significant decreases during everolimus treatment (P < 0.05). However, the decline in hemoglobin, WBC, and neutrophils attenuated by the 12th month (P ≥ 0.05). Aspartate transaminase (AST), Alanine transferase (ALT), total cholesterol (TC), and triglyceride (TG) increased significantly during everolimus treatment (P < 0.05), and these increases persisted throughout the year-long treatment. Hemoglobin decreased significantly more in male patients (- 15 vs - 6, P = 0.010), and AST showed a more significant increase in males (7.0 vs 3.0, P = 0.041). Platelet counts decreased significantly more in younger patients (≤ 30 years old) compared to older patients (- 50 vs - 14, P = 0.020).

CONCLUSION

Everolimus administration in TSC-RAML patients may increase hematologic risks, with male and younger patients potentially exhibiting greater susceptibility to these effects.

Promoted coagulant activity and disrupted blood-brain barrier depending on phosphatidylserine externalization of red blood cells exposed to ZnO nanoparticles

Zinc oxide nanoparticles (ZnO-NPs) are nanomaterials mainly produced and used worldwide. They translocate to circulatory systems from various exposure routes. While blood and endothelial cells are persistently exposed to circulating ZnO-NPs, the potential risks posed by ZnO-NPs to the cardiovascular system are largely unknown. Our study identified the potential risk of thrombosis and disturbance of the blood-brain barrier (BBB) by coagulant activity on red blood cells (RBCs) caused by ZnO-NPs. ZnO-NPs promoted the externalization of phosphatidylserine and the generation of microvesicles through an imbalance of intracellular mechanisms regulating procoagulant activity in human RBCs. The coagulation cascade leading to thrombin generation was promoted in ZnO-NPs-treated human RBCs. Combined with human RBCs, ZnO-NPs caused coagulant activity on isolated rat RBCs and rat venous thrombosis models. We identified the erythrophagocytosis of RBCs into brain endothelial cells via increased PS exposure induced by ZnO-NPs. Excessive erythrophagocytosis contributes to disrupting the BBB function of endothelial cells. ZnO-NPs increased the procoagulant activity of RBCs, causing venous thrombosis. Excessive erythrophagocytosis through ZnO-NPs-treated RBCs resulted in the dysfunction of BBB. Our study will help elucidate the potential risk ZnO-NPs exert on the cardiovascular system.

Nuclear receptor Rev-erbα role in fine-tuning erythropoietin gene expression

ABSTRACT

The regulation of red blood cell (RBC) homeostasis by erythropoietin (EPO) is critical for O2 transport and maintaining the adequate number of RBCs in vertebrates. Therefore, dysregulation in EPO synthesis results in disease conditions such as polycythemia in the case of excessive EPO production and anemia, which occurs when EPO is inadequately produced. EPO plays a crucial role in treating anemic patients; however, its overproduction can increase blood viscosity, potentially leading to fatal heart failure. Consequently, the identification of druggable transcription factors and their associated ligands capable of regulating EPO offers a promising therapeutic approach to address EPO-related disorders. This study unveils a novel regulatory mechanism involving 2 pivotal nuclear receptors (NRs), Rev-ERBA (Rev-erbα, is a truncation of reverse c-erbAa) and RAR-related orphan receptor A (RORα), in the control of EPO gene expression. Rev-erbα acts as a cell-intrinsic negative regulator, playing a vital role in maintaining erythropoiesis at the correct level. It accomplishes this by directly binding to newly identified response elements within the human and mouse EPO gene promoter, thereby repressing EPO production. These findings are further supported by the discovery that a Rev-erbα agonist (SR9011) effectively suppresses hypoxia-induced EPO expression in mice. In contrast, RORα functions as a positive regulator of EPO gene expression, also binding to the same response elements in the promoter to induce EPO production. Finally, the results of this study revealed that the 2 NRs, Rev-erbα and RORα, influence EPO synthesis in a negative and positive manner, respectively, suggesting that the modulating activity of these 2 NRs could provide a method to target disorders linked with EPO dysregulation.

Identifying and Analyzing Low Energy Availability in Athletes: The Role of Biomarkers and Red Blood Cell Turnover

Low energy availability (LEA) is a growing concern that can lead to several problems for athletes. However, adaptation to LEA occurs to maintain balance over time, making diagnosis difficult. In this review, we categorize LEA into two phases: the initial phase leading to adaptation and the phase in which adaptation is achieved and maintained. We review the influence of LEA on sports performance and health and discuss biomarkers for diagnosing LEA in each phase. This review also proposes future research topics for diagnosing LEA, with an emphasis on the recently discovered association between red blood cell turnover and LEA.

The melano-macrophage: The black leukocyte of fish immunity

Melanin and the process of melanin synthesis or melanogenesis have central roles in the immune system of insects, and production of melanin-synthesizing enzymes from their haemocytes may be induced following activation through danger signals. Melanin-containing macrophage-like cells have been extensively studied in amphibians and they are also present in reptiles. In fish, melano-macrophages are especially recognized with respect to melano-macrophage centres (MMCs), hypothesized to be analogues of germinal centres in secondary lymphoid organs of mammals and some birds. Melano-macrophages are in addition present in several inflammatory conditions, in particular melanised focal changes, or black spots, in the musculature of farmed Atlantic salmon, Salmo salar. Melanins are complex compounds that may be divided into different forms which all have the ability to absorb and scatter light. Other functions include the quenching of free radicals and a direct effect on the immune system. According to the common view held in the pigment cell community, vertebrate melanin synthesis with melanosome formation may only occur in cells of ectodermal origin. However, abundant information suggests that also myeloid cells of ectothermic vertebrates may be classified as melanocytes. Here, we discuss these opposing views and review relevant literature. Finally, we review the current status on the research concerning melanised focal muscle changes that represent the most severe quality problem in Norwegian salmon production, but also other diseases where melano-macrophages play important roles.

Apoptosis and eryptosis: similarities and differences

Eryptosis is a regulated cell death (RCD) of mature erythrocytes initially described as a counterpart of apoptosis for enucleated cells. However, over the recent years, a growing number of studies have emphasized certain differences between both cell death modalities. In this review paper, we underline the hallmarks of eryptosis and apoptosis and highlight resemblances and dissimilarities between both RCDs. We summarize and critically discuss differences in the impact of caspase-3, Ca2+ signaling, ROS signaling pathways, opposing roles of casein kinase 1α, protein kinase C, Janus kinase 3, cyclin-dependent kinase 4, and AMP-activated protein kinase to highlight a certain degree of divergence between apoptosis and eryptosis. This review emphasizes the crucial importance of further studies that focus on deepening our knowledge of cell death machinery and identifying novel differences between cell death of nucleated and enucleated cells. This might provide evidence that erythrocytes can be defined as viable entities capable of programmed cell destruction. Additionally, the revealed cell type-specific patterns in cell death can facilitate the development of cell death-modulating therapeutic agents.

Erythrocyte metabolism

Our aim is to present an updated overview of the erythrocyte metabolism highlighting its richness and complexity. We have manually collected and connected the available biochemical pathways and integrated them into a functional metabolic map. The focus of this map is on the main biochemical pathways consisting of glycolysis, the pentose phosphate pathway, redox metabolism, oxygen metabolism, purine/nucleoside metabolism, and membrane transport. Other recently emerging pathways are also curated, like the methionine salvage pathway, the glyoxalase system, carnitine metabolism, and the lands cycle, as well as remnants of the carboxylic acid metabolism. An additional goal of this review is to present the dynamics of erythrocyte metabolism, providing key numbers used to perform basic quantitative analyses. By synthesizing experimental and computational data, we conclude that glycolysis, pentose phosphate pathway, and redox metabolism are the foundations of erythrocyte metabolism. Additionally, the erythrocyte can sense oxygen levels and oxidative stress adjusting its mechanics, metabolism, and function. In conclusion, fine-tuning of erythrocyte metabolism controls one of the most important biological processes, that is, oxygen loading, transport, and delivery.

A new role for erythropoietin in the homeostasis of red blood cells

The regulation of red blood cell (RBC) homeostasis is widely assumed to rely on the control of cell production by erythropoietin (EPO) and the destruction of cells at a fixed, species-specific age. In this work, we show that such a regulatory mechanism would be a poor homeostatic solution to satisfy the changing needs of the body. Effective homeostatic control would require RBC lifespan to be variable and tightly regulated. We suggest that EPO may control RBC lifespan by determining CD47 expression in newly formed RBCs and SIRP-α expression in sinusoidal macrophages. EPO could also regulate the initiation and intensity of anti-RBC autoimmune responses that curtail RBC lifespan in some circumstances. These mechanisms would continuously modulate the rate of RBC destruction depending on oxygen availability. The control of RBC lifespan by EPO and autoimmunity emerges as a key mechanism in the homeostasis of RBCs.

Double-edged functions of hemopexin in hematological related diseases: from basic mechanisms to clinical application

It is now understood that hemolysis and the subsequent release of heme into circulation play a critical role in driving the progression of various diseases. Hemopexin (HPX), a heme-binding protein with the highest affinity for heme in plasma, serves as an effective antagonist against heme toxicity resulting from severe acute or chronic hemolysis. In the present study, changes in HPX concentration were characterized at different stages of hemolytic diseases, underscoring its potential as a biomarker for assessing disease progression and prognosis. In many heme overload-driven conditions, such as sickle cell disease, transfusion-induced hemolysis, and sepsis, endogenous HPX levels are often insufficient to provide protection. Consequently, there is growing interest in developing HPX therapeutics to mitigate toxic heme exposure. Strategies include HPX supplementation when endogenous levels are depleted and enhancing HPX's functionality through modifications, offering a potent defense against heme toxicity. It is worth noting that HPX may also exert deleterious effects under certain circumstances. This review aims to provide a comprehensive overview of HPX's roles in the progression and prognosis of hematological diseases. It highlights HPX-based clinical therapies for different hematological disorders, discusses advancements in HPX production and modification technologies, and offers a theoretical basis for the clinical application of HPX.

Warm autoimmune hemolytic anemia: new insights and hypotheses

PURPOSE OF REVIEW

Warm autoimmune hemolytic anemia (wAIHA) is the most common of the immune hemolytic anemias. Although there are numerous case reports and reviews regarding this condition, some of the unusual and more recent findings have not been fully defined and may be contentious. This review will provide insight into the common specificity of the warm autoantibodies and hypothesize a novel mechanism of wAIHA, that is proposed to be linked to the controversial subject of red blood cell senescence.

RECENT FINDINGS AND HYPOTHESES

It is now well established that band 3 on the red blood cell is the main target of autoantibodies in wAIHA. wAIHA targets the older red blood cells (RBCs) in about 80% of cases and, recently, it has been shown that the RBCs in these patients are aging faster than normal. It has been proposed that in these 80% of patients, that the autoantibody recognizes the senescent red blood cell antigen on band 3. It is further hypothesized that this autoantibody's production and potency has been exacerbated by hypersensitization to the RBC senescent antigen, which is processed through the adaptive immune system to create the pathogenic autoantibody. Recent publications have supported previous data that the senescent RBC antigen is exposed via a dynamic process, wherein oscillation of a band 3 internal loop flipping to the cell surface, creates a conformational neoantigen that is the RBC senescent antigen. It has also recently been shown that the cytokine profile in patients with wAIHA favors production of inflammatory cytokines/chemokines that includes interleukin-8 which can activate neutrophils to increase the oxidative stress on circulating RBCs to induce novel antigens, as has been postulated to favour exposure of the senescent RBC antigen.

SUMMARY

This manuscript reviews new findings and hypotheses regarding wAIHA and proposes a novel mechanism active in most wAIHA patients that is due to an exacerbation of normal RBC senescence.

The putatively high-altitude adaptation of macaque monkeys: Evidence from the fecal metabolome and gut microbiome

Animals living in high-altitude environments, such as the Tibetan Plateau, must face harsh environmental conditions (e.g., hypoxia, cold, and strong UV radiation). These animals' physiological adaptations (e.g., increased red cell production and turnover rate) might also be associated with the gut microbial response. Bilirubin is a component of red blood cell turnover or destruction and is excreted into the intestine and reduced to urobilinoids and/or urobilinogen by gut bacteria. Here, we found that the feces of macaques living in high-altitude regions look significantly browner (with a high concentration of stercobilin, a component from urobilinoids) than those living in low-altitude regions. We also found that gut microbes involved in urobilinogen reduction (e.g., beta-glucuronidase) were enriched in the high-altitude mammal population compared to the low-altitude population. Moreover, the spatial-temporal change in gut microbial function was more profound in the low-altitude macaques than in the high-altitude population, which might be attributed to profound changes in food resources in the low-altitude regions. Therefore, we conclude that a high-altitude environment's stress influences living animals and their symbiotic microbiota.

Induced Abortion and the Risk of Rh Sensitization

Importance

While population-level data suggest Rh immunoglobulin is unnecessary before 12 weeks' gestation, clinical evidence is limited. Thus, guidelines vary, creating confusion surrounding risks and benefits of Rh testing and treatment. As abortion care in traditional clinical settings becomes harder to access, many people are choosing to self-manage and need to know if ancillary blood type testing is necessary.

Objective

To determine how frequently maternal exposure to fetal red blood cells (fRBCs) exceeds the most conservative published threshold for Rh sensitization in induced first-trimester abortion.

Design, Setting, and Participants

Multicenter, observational, prospective cohort study using high-throughput flow cytometry to detect circulating fRBCs in paired maternal blood samples before and after induced first-trimester abortion (medication or procedural). Individuals undergoing induced first-trimester abortion before 12 weeks 0 days' gestation were included. Paired blood samples were available from 506 participants who underwent either medical (n = 319 [63.0%]) or procedural (n = 187 [37.0%]) abortion.

Exposure

Induced first-trimester abortion.

Main Outcomes and Measures

The primary outcome was the proportion of participants with fRBC counts above the sensitization threshold (125 fRBCs/5 million total RBCs) after induced first-trimester abortion.

Results

Among the 506 participants, the mean (SD) age was 27.4 (5.5) years, 313 (61.9%) were Black, and 123 (24.3%) were White. Three of the 506 participants had elevated fRBC counts at baseline; 1 of these patients had an elevated fRBC count following the abortion (0.2% [95% CI, 0%-0.93%]). No other participants had elevated fRBC counts above the sensitization threshold after induced first-trimester abortion. The median change from baseline was 0 fRBCs, with upper 95th and 99th percentiles of 24 and 35.6 fRBCs, respectively. Although there was a strong association between the preabortion and postabortion fRBC counts, no other baseline characteristic was significantly associated with postabortion fRBC count.

Conclusions and Relevance

Induced first-trimester abortion is not a risk factor for Rh sensitization, indicating that Rh testing and treatment are unnecessary before 12 weeks' gestation. This evidence may be used to inform international guidelines for Rh immunoglobulin administration following first-trimester induced abortion.

A light scatter based model relating erythrocyte vesiculation to lifetime in circulation

Methods for measuring erythrocyte age distribution are not available as a simple analytical tool. Most of them utilize the fluorescence or radioactive isotopes labeling to construct the age distribution and support physicians with aging indices of donor's erythrocytes. The age distribution of erythrocyte may be a useful snapshot of patient state over 120-days period of life. Previously, we introduced the enhanced assay of erythrocytes with measurement of 48 indices in four categories: concentration/content, morphology, aging and function (10.1002/cyto.a.24554). The aging category was formed by the indices based on the evaluation of the derived age of individual cells. The derived age does not exactly mean the real age of erythrocytes and its evaluation utilizes changes of cellular morphology during a lifespan. In this study, we are introducing the improved methodological approach that allows us to retrieve the derived age of individual erythrocytes, to construct the aging distribution, and to reform the aging category consisting of eight indices. The approach is based on the analysis of the erythrocyte vesiculation. The erythrocyte morphology is analyzed by scanning flow cytometry that measures the primary characteristics (diameter, thickness, and waist) of individual cells. The surface area (S) and sphericity index (SI) are calculated from the primary characteristics and the scattering diagram SI versus S is used in the evaluation of the derived age of each erythrocyte in a sample. We developed the algorithm to evaluate the derived age that provides eight indices in the aging category based on a model using light scatter features. The novel erythrocyte indices were measured for simulated cells and blood samples of 50 donors. We determined the first-ever reference intervals for these indices.

Metabolites of Life: Phosphate

The process of aging and escalating the failure of all body organs has become the center of interest in contemporary science and medicine. The leading role of phosphate-calcium tandem deficiency as a pacemaker of metabolic senescence has emerged recently. Most of the phosphates in the human body are stored in the bones, which seem to play a pivotal role in all metabolic and energetic processes. Bone metabolism combines physical activity with adaptive changes in the internal environment of the body, which is necessary for its survival. Phosphate-calcium signaling is the primary mechanism for controlling homeostasis and its recovery after exercise-induced disorders. Phosphates play an important role in the regulation of energy metabolism both by regulating postprandial glucose storage in the muscles and in the liver, as well as the distribution and adaptation of energy metabolites to the needs of the brain and skeletal muscles. The bone-driven energy metabolism is of decisive importance for maintaining all vital functions of the body organs, including their proper functioning and integrated interplay. The phosphate-calcium tandem contributes to the development and proper functioning of the organism, whereas energy dysmetabolism is the main cause of aging and the final termination of life.

Individual, Independent, and Joint Associations of Toxic Metals and Manganese on Hypertensive Disorders of Pregnancy: Results from the MIREC Canadian Pregnancy Cohort

BACKGROUND

Toxic metals, such as lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg), may be associated with a higher risk of gestational hypertension and preeclampsia, whereas manganese (Mn) is an essential metal that may be protective.

OBJECTIVES

We estimated the individual, independent, and joint associations of Pb, Cd, As, Hg, and Mn on the risk of developing gestational hypertension and preeclampsia in a cohort of Canadian women.

METHODS

Metal concentrations were analyzed in first and third trimester maternal blood (n=1,560). We measured blood pressure after 20 wk gestation to diagnose gestational hypertension, whereas proteinuria and other complications defined preeclampsia. We estimated individual and independent (adjusted for coexposure) relative risks (RRs) for each doubling of metal concentrations and examined interactions between toxic metals and Mn. We used quantile g-computation to estimate the joint effect of trimester-specific exposures.

RESULTS

Each doubling of third trimester Pb (RR=1.54; 95% CI: 1.06, 2.22) and first trimester blood As (RR=1.25; 95% CI: 1.01, 1.58) was independently associated with a higher risk of developing preeclampsia. First trimester blood As (RR=3.40; 95% CI: 1.40, 8.28) and Mn (RR=0.63; 95% CI: 0.42, 0.94) concentrations were associated with a higher and lower risk, respectively, of developing gestational hypertension. Mn modified the association with As such that the deleterious association with As was stronger at lower concentrations of Mn. First trimester urinary dimethylarsinic acid concentrations were not associated with gestational hypertension (RR=1.31; 95% CI: 0.60, 2.85) or preeclampsia (RR=0.92; 95% CI: 0.68, 1.24). We did not observe overall joint effects for blood metals.

DISCUSSION

Our results confirm that even low blood Pb concentrations are a risk factor for preeclampsia. Women with higher blood As concentrations combined with lower Mn in early pregnancy were more likely to develop gestational hypertension. These pregnancy complications impact maternal and neonatal health. Understanding the contribution of toxic metals and Mn is of public health importance. https://doi.org/10.1289/EHP10825.

Association of change in haemoglobin A1c with adverse perinatal outcomes in women with pregestational diabetes

AIMS

To determine whether a net decline in glycosylated haemoglobin (HbA_1c ) from early to late pregnancy is associated with lower risk of adverse perinatal outcomes at delivery among women with pregestational diabetes.

METHODS

A retrospective analysis from 2012 to 2016 at a tertiary care centre. The exposure was the net change in HbA_1c from early (<20 weeks gestation) to late pregnancy (≥20 weeks gestation). Primary outcomes were large for gestational age (LGA) and neonatal hypoglycaemia. The association between outcomes per 6 mmol/mol (0.5%) absolute decrease in HbA_1c was evaluated using modified Poisson regression, and adjusted for age, body mass index, White Class, early HbA_1c and haemoglobin and gestational age at HbA_1c measurement and delivery.

RESULTS

Among 347 women with pregestational diabetes, HbA_1c was assessed in early (9 weeks [IQR 7,13]) and late pregnancy (31 weeks [IQR 29,34]). Mean HbA_1c decreased from early (59 mmol/mol [7.5%]) to late (47 mmol/mol [6.5%]) pregnancy. Each 6 mmol/mol (0.5%) absolute decrease in HbA_1c was associated with a 12% reduced risk of LGA infant (30%, aRR:0.88; 95% CI:0.81,0.95), and a 7% reduced risk of neonatal hypoglycaemia (35%, aRR:0.93; 95% CI:0.87,0.99). Preterm birth (36%, aRR:0.93; 95% CI:0.89,0.98) and neonatal intensive care unit admission (55%, aRR:0.95; 95% CI:0.91,0.98) decreased with a net decline in HbA_1c , but not caesarean delivery, pre-eclampsia, shoulder dystocia and respiratory distress syndrome.

CONCLUSIONS

Women with pregestational diabetes with a reduction in HbA_1c may have fewer infants born LGA or with neonatal hypoglycaemia. Repeated assessment of HbA_1c may provide an additional measure of glycaemic control.

What Should Be Responsible for Eryptosis in Chronic Kidney Disease?

BACKGROUND

Renal anemia is an important complication of chronic kidney disease (CKD). In addition to insufficient secretion of erythropoietin (EPO) and erythropoiesis disorders, the impact of eryptosis on renal anemia demands attention. However, a systemic analysis concerning the pathophysiology of eryptosis has not been expounded.

SUMMARY

The complicated conditions in CKD patients, including oxidative stress, osmotic stress, metabolic stress, accumulation of uremic toxins, and iron deficiency, affect the normal skeleton structure of red blood cells (RBCs) and disturbs ionic homeostasis, causing phosphatidylserine to translocate to the outer lobules of the RBC membrane that leads to early elimination and/or shortening of the RBC lifespan. Inadequate synthesis of RBCs cannot compensate for their accelerated destruction, thus exacerbating renal anemia. Meanwhile, EPO treatment alone will not reverse renal anemia. A variety of eryptosis inhibitors have so far been found, but evidence of their effectiveness in the treatment of CKD remains to be established.

KEY MESSAGES

In this review, the pathophysiological processes and factors influencing eryptosis in CKD were elucidated. The aim of this review was to underline the importance of eryptosis in renal anemia and determine some promising research directions or possible therapeutic targets to correct anemia in CKD.

Olive Oil Phenols Prevent Mercury-Induced Phosphatidylserine Exposure and Morphological Changes in Human Erythrocytes Regardless of Their Different Scavenging Activity

Phosphatidylserine (PS) translocation to the external membrane leaflet represents a key mechanism in the pathophysiology of human erythrocytes (RBC) acting as an "eat me" signal for the removal of aged/stressed cells. Loss of physiological membrane asymmetry, however, can lead to adverse effects on the cardiovascular system, activating a prothrombotic activity. The data presented indicate that structurally related olive oil phenols prevent cell alterations induced in intact human RBC exposed to HgCl₂ (5-40 µM) or Ca²⁺ ionophore (5 µM), as measured by hallmarks including PS exposure, reactive oxygen species generation, glutathione depletion and microvesicles formation. The protective effect is observed in a concentration range of 1-30 µM, hydroxytyrosol being the most effective; its in vivo metabolite homovanillic alcohol still retains the biological activity of its dietary precursor. Significant protection is also exerted by tyrosol, in spite of its weak scavenging activity, indicating that additional mechanisms are involved in the protective effect. When RBC alterations are mediated by an increase in intracellular calcium, the protective effect is observed at higher concentrations, indicating that the selected phenols mainly act on Ca²⁺-independent mechanisms, identified as protection of glutathione depletion. Our findings strengthen the nutritional relevance of olive oil bioactive compounds in the claimed health-promoting effects of the Mediterranean Diet.

Proteome remodeling and organelle clearance in mammalian terminal erythropoiesis

PURPOSE OF REVIEW

The differentiation from colony forming unit-erythroid (CFU-E) cells to mature enucleated red blood cells is named terminal erythropoiesis in mammals. Apart from enucleation, several unique features during these developmental stages include proteome remodeling and organelle clearance that are important to achieve hemoglobin enrichment. Here, we review the recent advances in the understanding of novel regulatory mechanisms in these processes, focusing on the master regulators that link these major events during terminal erythropoiesis.

RECENT FINDINGS

Comprehensive proteomic studies revealed a mismatch of protein abundance to their corresponding transcript abundance, which indicates that the proteome remodeling is regulated in a complex way from transcriptional control to posttranslational modifications. Key regulators in organelle clearance were also found to play critical roles in proteome remodeling.

SUMMARY

These studies demonstrate that the complexity of terminal erythropoiesis is beyond the conventional transcriptomic centric perspective. Posttranslational modifications such as ubiquitination are critical in terminal erythroid proteome remodeling that is also closely coupled with organelle clearance.

A SIRPαFc Fusion Protein Conjugated With the Collagen-Binding Domain for Targeted Immunotherapy of Non-Small Cell Lung Cancer

The SIRPαFc fusion protein can block the immunosuppressive CD47-SIRPα signal between macrophages and tumor cells as a decoy receptor and has demonstrated its immunotherapeutic efficacy in various tumors. However, its clinical application was limited because of the potential hematologic toxicity. The heptapeptide “TKKTLRT” is a collagen-binding domain (CBD) which can bind collagen specifically. Herein, we aim to improve the tumor targeting of SIRPαFc and therefore avoid its unnecessary exposure to normal cells through synthesizing a TKKTLRT–SIRPαFc conjugate. Experiments at molecular and cellular levels indicate that the TKKTLRT–SIRPαFc conjugate-derived collagen-binding affinity and the introduction of CBD did not impact the CD47-binding affinity as well as its phagocytosis-promoting effect on NSCLC cells. In vivo distribution experiments showed that CBD–SIRPαFc accumulated in tumor tissue more effectively compared to unmodified SIRPαFc, probably due to the exposed collagen in the tumor vascular endothelium and stroma resulting from the abnormal vessel structure. On an A549 NSCLC nude mouse xenograft model, CBD–SIRPαFc presented more stable and effective antitumor efficacy than SIRPαFc, along with significantly increased CD11b⁺F4/80⁺ macrophages especially MHC II⁺ M1 macrophages within tumors. All of these results revealed that CBD brought a tumor-targeting ability to the SIRPαFc fusion protein, which contributed to the enhanced antitumor immune response. Altogether, the CBD–SIRPαFc conjugate may have the potential to be an effective tumor immunotherapy with improved antitumor efficacy but less non-tumor-targeted side effect.

Even patients with mild COVID-19 symptoms after SARS-CoV-2 infection show prolonged altered red blood cell morphology and rheological parameters

Infection with the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and the associated coronavirus disease-19 (COVID-19) might affect red blood cells (RBC); possibly altering oxygen supply. However, investigations of cell morphology and RBC rheological parameters during a mild disease course are lacking and thus, the aim of the study. Fifty individuals with mild COVID-19 disease process were tested after the acute phase of SARS-CoV-2 infection (37males/13 females), and the data were compared to n = 42 healthy controls (30 males/12 females). Analysis of venous blood samples, taken at rest, revealed a higher percentage of permanently elongated RBC and membrane extensions in COVID-19 patients. Haematological parameters and haemoglobin concentration, MCH and MCV in particular, were highly altered in COVID-19. RBC deformability and deformability under an osmotic gradient were significantly reduced in COVID-19 patients. Higher RBC-NOS activation was not capable to at least in part counteract these reductions. Impaired RBC deformability might also be related to morphological changes and/or increased oxidative state. RBC aggregation index remained unaffected. However, higher shear rates were necessary to balance the aggregation-disaggregation in COVID-19 patients which might be, among others, related to morphological changes. The data suggest prolonged modifications of the RBC system even during a mild COVID-19 disease course.

Engineered RBCs Encapsulating Antigen Induce Multi-Modal Antigen-Specific Tolerance and Protect Against Type 1 Diabetes

Antigen-specific therapies that suppress autoreactive T cells without inducing systemic immunosuppression are a much-needed treatment for autoimmune diseases, yet effective strategies remain elusive. We describe a microfluidic Cell Squeeze® technology to engineer red blood cells (RBCs) encapsulating antigens to generate tolerizing antigen carriers (TACs). TACs exploit the natural route of RBC clearance enabling tolerogenic presentation of antigens. TAC treatment led to antigen-specific T cell tolerance towards exogenous and autoantigens in immunization and adoptive transfer mouse models of type 1 diabetes (T1D), respectively. Notably, in several accelerated models of T1D, TACs prevented hyperglycemia by blunting effector functions of pathogenic T cells, particularly in the pancreas. Mechanistically, TACs led to impaired trafficking of diabetogenic T cells to the pancreas, induced deletion of autoreactive CD8 T cells and expanded antigen specific Tregs that exerted bystander suppression. Our results highlight TACs as a novel approach for reinstating immune tolerance in CD4 and CD8 mediated autoimmune diseases.

Dysregulation in erythrocyte dynamics caused by SARS-CoV-2 infection: possible role in shuffling the homeostatic puzzle during COVID-19

Introduction

The evolving COVID-19 pandemic became a hallmark in human history, not only by changing lifestyles, but also by enriching scientific knowledge on viral infection and its consequences.

Objective

Although the management of cardiorespiratory changes is pivotal to a favorable prognosis during severe clinical findings, dysregulation of other systems caused by SARS-CoV-2 infection may imbalance erythrocyte dynamics, such as a bidirectional positive feedback loop pathophysiology.

Method and Results

Recent evidence shows that SARS-CoV-2 is capable of affecting the genetics and dynamics of erythrocytes and this coexists with a non-homeostatic function of cardiovascular, respiratory and renal systems during COVID-19. In hypothesis, SARS-CoV-2-induced systematical alterations of erythrocytes dynamics would constitute a setpoint for COVID-19-related multiple organ failure syndrome and death.

Conclusion

The present review covers the most frequent erythrocyte-related non-homeostatic findings during COVID-19 capable of providing mechanistic clues of SARS-CoV-2-induced infection and inspiring therapeutic-oriented scientific evidence.

Progress of CD47 immune checkpoint blockade agents in anticancer therapy: a hematotoxic perspective

CD47, a transmembrane protein, acts as a "do not eat me" signal that is overexpressed in many tumor cell types, thereby forming a signaling axis with its ligand signal regulatory protein alpha (SIRPα) and enabling the tumor cells to escape from macrophage-mediated phagocytosis. Several clinical trials with CD47 targeting agents are underway and have achieved impressive results preliminarily. However, hematotoxicity (particularly anemia) has emerged as the most common side effect that cannot be neglected. In the development of CD47 targeting agents, various methods have been used to mitigate this toxicity. In this review, we summarized five strategies used to alleviate CD47 blockade-induced hematotoxicity, as follows: change in the mode of administration; dual targeting bispecific antibodies of CD47; CD47 antibodies/SIRPα fusion proteins with negligible red blood cell binding; anti-SIRPα antibodies; and glutaminyl-peptide cyclotransferase like inhibitors. With these strategies, the development of CD47 targeting agents can be improved.

Concise review: how do red blood cells born, live, and die?

The average life cycle of a human RBC is approximately 120 days. Generally, by this point, the cell is worn out and damaged. RBCs pass through both the spleen and liver, where specialised immune cells called macrophages are found. Macrophages recognise when an RBC is spent, and undergo a process called phagocytosis where they digest the cell. In this process, the iron in haemoglobin is recycled for use in new blood cells and the hem molecule is degraded, conjugated to bilirubin, and eliminated from the body. All the other cellular proteins are either recycled or eliminated. Historically, this process was thought to occur exclusively in the spleen, but recent studies have shown that it occurs in the bone marrow. The RBC has been analysed from many perspectives: cytological, haematological, and immunological, as well as from the focus of molecular biology, biophysics, and mathematics. Here we analyse how are red blood cells born and how they live and die in a brief overview of the whole process with special mention of the morphological aspects from bone marrow and spleen provided by transmission and scanning electron microscopy.

Nanoscale Changes on RBC Membrane Induced by Storage and Ionizing Radiation: A Mini-Review

The storage lesions and the irradiation of blood cellular components for medical procedures in blood banks are events that may induce nanochanges in the membrane of red blood cells (RBCs). Alterations, such as the formation of pores and vesicles, reduce flexibility and compromise the overall erythrocyte integrity. This review discusses the alterations on erythrocytic lipid membrane bilayer through their characterization by confocal scanning microscopy, Raman, scanning electron microscopy, and atomic force microscopy techniques. The interrelated experimental results may address and shed light on the correlation of biomechanical and biochemical transformations induced in the membrane and cytoskeleton of stored and gamma-irradiated RBC. To highlight the main advantages of combining these experimental techniques simultaneously or sequentially, we discuss how those outcomes observed at micro- and nanoscale cell levels are useful as biomarkers of cell aging and storage damage.

Efficient encapsulation of functional proteins into erythrocytes by controlled shear-mediated membrane deformation

Red blood cells (RBCs) are attractive carriers of biomolecular payloads due to their biocompatibility and the ability to shelter their encapsulated cargo. Commonly employed strategies to encapsulate payloads into RBCs, such as hypotonic shock, membrane fusion or electroporation, often suffer from low throughput and unrecoverable membrane impairment. This work describes an investigation of a method to encapsulate protein payloads into RBCs by controlling membrane deformation either transiently or extendedly in a microfluidic channel. Under the optimized conditions, the loading efficiency of enhanced green fluorescent protein into mouse RBCs increased was about 2.5- and 4-fold compared to that with osmotic entrapment using transient and extended deformation, respectively. Significantly, mouse RBCs loaded with human arginase exhibit higher enzymatic activity and membrane integrity compared to their counterparts loaded by osmotic entrapment. These features together with the fact that this shear-mediated encapsulation strategy allows loading with physiological buffers highlight the key advantages of this approach compared to traditional osmotic entrapment.

Erythrocytes: Central Actors in Multiple Scenes of Atherosclerosis

The development and progression of atherosclerosis (ATH) involves lipid accumulation, oxidative stress and both vascular and blood cell dysfunction. Erythrocytes, the main circulating cells in the body, exert determinant roles in the gas transport between tissues. Erythrocytes have long been considered as simple bystanders in cardiovascular diseases, including ATH. This review highlights recent knowledge concerning the role of erythrocytes being more than just passive gas carriers, as potent contributors to atherosclerotic plaque progression. Erythrocyte physiology and ATH pathology is first described. Then, a specific chapter delineates the numerous links between erythrocytes and atherogenesis. In particular, we discuss the impact of extravasated erythrocytes in plaque iron homeostasis with potential pathological consequences. Hyperglycaemia is recognised as a significant aggravating contributor to the development of ATH. Then, a special focus is made on glycoxidative modifications of erythrocytes and their role in ATH. This chapter includes recent data proposing glycoxidised erythrocytes as putative contributors to enhanced atherothrombosis in diabetic patients.

Red Blood Cells: Tethering, Vesiculation, and Disease in Micro-Vascular Flow

The red blood cell has become implicated in the progression of a range of diseases; mechanisms by which red cells are involved appear to include the transport of inflammatory species via red cell-derived vesicles. We review this role of RBCs in diseases such as diabetes mellitus, sickle cell anemia, polycythemia vera, central retinal vein occlusion, Gaucher disease, atherosclerosis, and myeloproliferative neoplasms. We propose a possibly unifying, and novel, paradigm for the inducement of RBC vesiculation during vascular flow of red cells adhered to the vascular endothelium as well as to the red pulp of the spleen. Indeed, we review the evidence for this hypothesis that links physiological conditions favoring both vesiculation and enhanced RBC adhesion and demonstrate the veracity of this hypothesis by way of a specific example occurring in splenic flow which we argue has various renderings in a wide range of vascular flows, in particular microvascular flows. We provide a mechanistic basis for membrane loss and the formation of lysed red blood cells in the spleen that may mediate their turnover. Our detailed explanation for this example also makes clear what features of red cell deformability are involved in the vesiculation process and hence require quantification and a new form of quantitative indexing.

The Mystery of Red Blood Cells Extracellular Vesicles in Sleep Apnea with Metabolic Dysfunction

Sleep is very important for overall health and quality of life, while sleep disorder has been associated with several human diseases, namely cardiovascular, metabolic, cognitive, and cancer-related alterations. Obstructive sleep apnea (OSA) is the most common respiratory sleep-disordered breathing, which is caused by the recurrent collapse of the upper airway during sleep. OSA has emerged as a major public health problem and increasing evidence suggests that untreated OSA can lead to the development of various diseases including neurodegenerative diseases. In addition, OSA may lead to decreased blood oxygenation and fragmentation of the sleep cycle. The formation of free radicals or reactive oxygen species (ROS) can emerge and react with nitric oxide (NO) to produce peroxynitrite, thereby diminishing the bioavailability of NO. Hypoxia, the hallmark of OSA, refers to a decline of tissue oxygen saturation and affects several types of cells, playing cell-to-cell communication a vital role in the outcome of this interplay. Red blood cells (RBCs) are considered transporters of oxygen and nutrients to the tissues, and these RBCs are important interorgan communication systems with additional functions, including participation in the control of systemic NO metabolism, redox regulation, blood rheology, and viscosity. RBCs have been shown to induce endothelial dysfunction and increase cardiac injury. The mechanistic links between changes of RBC functional properties and cardiovascular are largely unknown. Extracellular vesicles (EVs) are secreted by most cell types and released in biological fluids both under physiological and pathological conditions. EVs are involved in intercellular communication by transferring complex cargoes including proteins, lipids, and nucleic acids from donor cells to recipient cells. Advancing our knowledge about mechanisms of RBC-EVs formation and their pathophysiological relevance may help to shed light on circulating EVs and to translate their application to clinical practice. We will focus on the potential use of RBC-EVs as valuable diagnostic and prognostic biomarkers and state-specific cargoes, and possibilities as therapeutic vehicles for drug and gene delivery. The use of RBC-EVs as a precision medicine for the diagnosis and treatment of the patient with sleep disorder will improve the prognosis and the quality of life in patients with cardiovascular disease (CVD).

Evaluation of cellular changes in blood stored for transfusion at Bungoma County Referral Hospital, Kenya

Introduction

during the storage of transfusion blood, it may undergo a series of cellular changes that in speculation could be the reason behind the risk of using prolonged stored blood. It's important therefore to monitor the cellular changes that may reduce its survival and function. The objective was to assess the cellular changes in whole blood stored for transfusion at Bungoma county referral hospital.

Methods

a single center, prospective and observational study design involving 20 randomly selected donor blood units in citrate phosphate dextrose adenine (CPDA-1) anticoagulant was employed, cellular changes were evaluated for 35 days. The changes were tested using the Celtac F Haematology analyzer. Statistical Analysis of variance was employed in the descriptive statistics. All the investigation was executed using statistical package for social sciences (SPSS V.23). Results were regarded as significant at P<0.05. Results were presented in tables and charts.

Results

at the end of the 35 days blood storage at blood bank conditions, WBC, RBC, platelets counts and MCHC decreased significantly (P<0.0001, =0.0182, <0.0001, =0.0035). The MCV, HCT and MCH increased significantly (P <0.0001, =0.0003, =0.0115) while HGB had insignificant variance (P =0.4185).

Conclusion

platelets, WBC, RBC counts, and indices are significantly altered in stored blood especially when stored over two weeks based on most of the cellular components analyzed in this study. The study, therefore, recommends the utilization of fresh blood to avoid the adverse outcome of cellular changes of reserved blood.

18F-fluorodeoxyglucose positron emission tomography-computed tomography for assessing organ distribution of stressed red blood cells in mice

Red blood cells (RBCs) stressed by high temperature are similar to senescent or damaged RBCs in pathological conditions. RBCs can be efficiently labelled with ¹⁸F-fluorodeoxyglucose (FDG). The aim of this study was to assess stressed RBCs erythrophagocytosis and organ distribution in vivo with the application of ¹⁸F-FDG PET/CT. RBCs were induced under high temperature (48 °C) to prepare stressed RBCs. Fluorescence-activated cell sorting (FACS) was used to analyse reactive oxygen species (ROS) generation, intracellular Ca²⁺ concentration and membrane phosphatidylserine (PS) externalization of RBCs. ¹⁸F-FDG was used to label RBCs and assess the erythrophagocytosis. Finally, ¹⁸F-FDG PET/CT was applied to reveal and measure the organ distribution of stressed RBCs in mice. Compared with untreated RBCs, stressed RBCs decreased in cell volume and increased in ROS level, intracellular Ca²⁺ concentration, and PS exposure. RBCs could be labelled by ¹⁸F-FDG. Stressed RBCs tended to be phagocytosed by macrophages via assessment of FACS and radioactivity. ¹⁸F-FDG PET/CT imaging showed that stressed RBCs were mainly trapped in spleen, while untreated RBCs remained in circulation system. Thus, stressed RBCs can be effectively labelled by ¹⁸F-FDG and tend to be trapped in spleen of mice as assessed by PET/CT.

Sub-Fractions of Red Blood Cells Respond Differently to Shear Exposure Following Superoxide Treatment

Simple Summary

Deformation of red blood cells (RBCs) is essential in order to pass through the smallest blood vessels. This cell function is impaired in the presence of high levels of free radicals and shear stress that highly exceeds the physiological range. In contrast, shear stress within the physiological range positively affects RBC function. RBCs are a heterogeneous cell population in terms of RBC age with different RBC deformability described for young and old RBCs, but whether these different sub-populations tolerate mechanical and oxidative stress to the same extent remains unknown. The results of the present investigation revealed lower RBC deformability of old RBCs compared to young RBCs and comparable reductions in RBC deformability of the sub-populations caused by free radicals. Physiological shear stress did not further affect free radical content within the RBCs and reversed the deleterious effects of free radicals on RBC deformability of old RBCs only by improving RBC deformability. The changes were aimed to be explained by changes in the formation of nitric oxide (NO), but outputs of NO generation appeared dependent on cell age. These novel findings highlight a yet less-described complex relation between shear stress, free radicals, and RBC mechanics.

Abstract

Red blood cell (RBC) deformability is an essential component of microcirculatory function that appears to be enhanced by physiological shear stress, while being negatively affected by supraphysiological shears and/or free radical exposure. Given that blood contains RBCs with non-uniform physical properties, whether all cells equivalently tolerate mechanical and oxidative stresses remains poorly understood. We thus partitioned blood into old and young RBCs which were exposed to phenazine methosulfate (PMS) that generates intracellular superoxide and/or specific mechanical stress. Measured RBC deformability was lower in old compared to young RBCs. PMS increased total free radicals in both sub-populations, and RBC deformability decreased accordingly. Shear exposure did not affect reactive species in the sub-populations but reduced RBC nitric oxide synthase (NOS) activation and intriguingly increased RBC deformability in old RBCs. The co-application of PMS and shear exposure also improved cellular deformability in older cells previously exposed to reactive oxygen species (ROS), but not in younger cells. Outputs of NO generation appeared dependent on cell age; in general, stressors applied to younger RBCs tended to induce S-nitrosylation of RBC cytoskeletal proteins, while older RBCs tended to reflect markers of nitrosative stress. We thus present novel findings pertaining to the interplay of mechanical stress and redox metabolism in circulating RBC sub-populations.

Hyperhaemolytic Syndrome in Sickle Cell Disease: Clearing the Cobwebs

Sickle cell disease (SCD) presents with a dynamic background of haemolysis and deepening anaemia. This increases the demand for transfusion if any additional strain on haemopoiesis is encountered due to any other physiological or pathological causes. Patients with cerebrovascular accidents are placed on chronic blood transfusion; those with acute sequestration and acute chest syndrome are likewise managed with blood transfusion. These patients are prone to develop complications of blood transfusion including alloimmunization and hyperhaemolytic syndrome (HHS). This term is used to describe haemolysis of both transfused and "own" red cells occurring during or post-transfusion in sickle cell patients. Hyperhaemolysis results in worsening post-transfusion haemoglobin due attendant haemolysis of both transfused and autologous red cells. The mechanism underlying this rare and usually fatal complication of SCD has been thought to be secondary to changes in the red cell membrane with associated immunological reactions against exposed cell membrane phospholipids. The predisposition to HHS in sickle cell is also varied and the search for a prediction pattern or value has been evasive. This review discusses the pathogenesis, risk factors and treatment of HHS, elaborating on what is known of this rare condition.

Relation between Exercise Performance and Blood Storage Condition and Storage Time in Autologous Blood Doping

Professional athletes are expected to continuously improve their performance, and some might also use illegal methods-e.g., autologous blood doping (ABD)-to achieve improvements. This article applies a systematic literature review to investigate differences in the ABD methods and the related performance and blood parameters owing to different storage conditions-cryopreservation (CP) and cold storage (CS)-and different storage durations. The literature research resulted in 34 original articles. The majority of currently published studies employed CS during ABD. This contrasts to the applied storage technique in professional sports, which was mainly reported to be CP. The second outcome of the literature research revealed large differences in the storage durations applied, which were in the range of one day to 17 weeks between blood sampling and re-infusion, which might affect recovery of the red blood cell mass and thus performance outcome related to ABD. Data revealed that performance parameters were positively affected by ABD when a minimal storage duration of four weeks was adhered. This article identified a need for further research that reflect common ABD practice and its real effects on performance parameters, but also on related blood parameters in order to develop valid and reliable ABD detection methods.

The Role of Eryptosis in the Pathogenesis of Renal Anemia: Insights From Basic Research and Mathematical Modeling

Red blood cells (RBC) are the most abundant cells in the blood. Despite powerful defense systems against chemical and mechanical stressors, their life span is limited to about 120 days in healthy humans and further shortened in patients with kidney failure. Changes in the cell membrane potential and cation permeability trigger a cascade of events that lead to exposure of phosphatidylserine on the outer leaflet of the RBC membrane. The translocation of phosphatidylserine is an important step in a process that eventually results in eryptosis, the programmed death of an RBC. The regulation of eryptosis is complex and involves several cellular pathways, such as the regulation of non-selective cation channels. Increased cytosolic calcium concentration results in scramblase and floppase activation, exposing phosphatidylserine on the cell surface, leading to early clearance of RBCs from the circulation by phagocytic cells. While eryptosis is physiologically meaningful to recycle iron and other RBC constituents in healthy subjects, it is augmented under pathological conditions, such as kidney failure. In chronic kidney disease (CKD) patients, the number of eryptotic RBC is significantly increased, resulting in a shortened RBC life span that further compounds renal anemia. In CKD patients, uremic toxins, oxidative stress, hypoxemia, and inflammation contribute to the increased eryptosis rate. Eryptosis may have an impact on renal anemia, and depending on the degree of shortened RBC life span, the administration of erythropoiesis-stimulating agents is often insufficient to attain desired hemoglobin target levels. The goal of this review is to indicate the importance of eryptosis as a process closely related to life span reduction, aggravating renal anemia.

Association of Improved Periconception Hemoglobin A1c With Pregnancy Outcomes in Women With Diabetes

IMPORTANCE

Prepregnancy diabetes is associated with higher perinatal and maternal morbidity, especially if periconception glycemic control is suboptimal. It is not known whether improved glycemic control from preconception to early pregnancy and midpregnancy periods can reduce the risk of adverse perinatal and maternal outcomes.

OBJECTIVE

To determine whether a net decline in glycated hemoglobin A1c (HbA1c) from preconception to the first half of pregnancy is associated with a lower risk of adverse outcomes for mother and child.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study was completed in all of Ontario, Canada, from 2007 to 2018. Included were births among women with prepregnancy diabetes whose HbA1c was measured within 90 days preconception and again from conception through 21 weeks completed gestation (early pregnancy to midpregnancy). Statistical analysis was performed from July to September 2020.

EXPOSURES

Net decrease in HbA1c from preconception to early pregnancy and midpregnancy.

MAIN OUTCOMES AND MEASURES

The main outcome was a congenital anomaly from birth to age 1 year. Other outcomes included preterm birth or perinatal mortality among offspring as well as severe maternal morbidity (SMM) or death among mothers. Adjusted relative risks (aRRs) were calculated per 0.5% absolute net decline in HbA1c from preconception up to early pregnancy and midpregnancy, adjusting for maternal age at conception, preconception HbA1c and hemoglobin concentration, and gestational age at HbA1c measurement.

RESULTS

A total of 3459 births were included, with a mean (SD) maternal age of 32.6 (5.0) years at conception. Overall, the mean (SD) HbA1c decreased from 7.2% (1.6%) preconception to 6.4% (1.1%) in early pregnancy to midpregnancy. There were 497 pregnancies (14.4%) with a congenital anomaly, with an aRR of 0.94 (95% CI, 0.89-0.98) per 0.5% net decrease in HbA1c, including for cardiac anomalies (237 infants; aRR, 0.89; 95% CI, 0.84-0.95). The risk was also reduced for preterm birth (847 events; aRR, 0.89; 95% CI, 0.86-0.91). SMM or death occurred among 191 women (5.5%), with an aRR of 0.90 (95% CI, 0.84-0.96) per 0.5% net decrease in HbA1c.

CONCLUSIONS AND RELEVANCE

These findings suggest that women with prepregnancy diabetes who achieve a reduction in HbA1c may have improved perinatal and maternal outcomes. Further study is recommended to determine the best combination of factors, such as lifestyle changes and/or glucose-lowering medications, that can influence periconception HbA1c reduction.

Aging-associated changes in CD47 arrangement and interaction with thrombospondin-1 on red blood cells visualized by super-resolution imaging

CD47 serves as a ligand for signaling regulatory protein α (SIRPα) and as a receptor for thrombospondin-1 (TSP-1). Although CD47, TSP-1, and SIRPα are thought to be involved in the clearance of aged red blood cells (RBCs), aging-associated changes in the expression and interaction of these molecules on RBCs have been elusive. Using direct stochastic optical reconstruction microscopy (dSTORM)-based imaging and quantitative analysis, we can report that CD47 molecules on young RBCs reside as nanoclusters with little binding to TSP-1, suggesting a minimal role for TSP-1/CD47 signaling in normal RBCs. On aged RBCs, CD47 molecules decreased in number but formed bigger and denser clusters, with increased ability to bind TSP-1. Exposure of aged RBCs to TSP-1 resulted in a further increase in the size of CD47 clusters via a lipid raft-dependent mechanism. Furthermore, CD47 cluster formation was dramatically inhibited on thbs1-/- mouse RBCs and associated with a significantly prolonged RBC lifespan. These results indicate that the strength of CD47 binding to its ligand TSP-1 is predominantly determined by the distribution pattern and not the amount of CD47 molecules on RBCs, and offer direct evidence for the role of TSP-1 in phagocytosis of aged RBCs. This study provides clear nanoscale pictures of aging-associated changes in CD47 distribution and TSP-1/CD47 interaction on the cell surface, and insights into the molecular basis for how these molecules coordinate to remove aged RBCs.

CD47 as a Potential Target to Therapy for Infectious Diseases

The integrin associated protein (CD47) is a widely and moderately expressed glycoprotein in all healthy cells. Cancer cells are known to induce increased CD47 expression. Similar to cancer cells, all immune cells can upregulate their CD47 surface expression during infection. The CD47-SIRPa interaction induces an inhibitory effect on macrophages and dendritic cells (dendritic cells) while CD47-thrombospondin-signaling inhibits T cells. Therefore, the disruption of the CD47 interaction can mediate several biologic functions. Upon the blockade and knockout of CD47 reveals an immunosuppressive effect of CD47 during LCMV, influenza virus, HIV-1, mycobacterium tuberculosis, plasmodium and other bacterial pneumonia infections. In our recent study we shows that the blockade of CD47 using the anti-CD47 antibody increases the activation and effector function of macrophages, dendritic cells and T cells during viral infection. By enhancing both innate and adaptive immunity, CD47 blocking antibody promotes antiviral effect. Due to its broad mode of action, the immune-stimulatory effect derived from this antibody could be applicable in nonresolving and (re)emerging infections. The anti-CD47 antibody is currently under clinical trial for the treatment of cancer and could also have amenable therapeutic potential against infectious diseases. This review highlights the immunotherapeutic targeted role of CD47 in the infectious disease realm.

Antirhea borbonica Aqueous Extract Protects Albumin and Erythrocytes from Glycoxidative Damages

Diabetes constitutes a major health problem associated with severe complications. In hyperglycemic conditions, chronically increased oxidation and glycation of circulating components lead to advanced glycation end-products (AGEs) formation, a key contributor in diabetes complication progression. In line with literature documenting the beneficial properties of herbal teas, this study evaluates the antioxidant/glycant properties of Antirhea borbonica (Ab). Ab aqueous extract effects were tested on human albumin or erythrocytes submitted to methyl glyoxal-mediated glycoxidative damages. By using mass spectrometry, Ab aqueous extracts revealed to be rich in polyphenols. All tested biomarkers of oxidation and glycation, such as AGE, ketoamine, oxidized thiol groups, were decreased in albumin when glycated in the presence of Ab aqueous extract. Ab extract preserve erythrocyte from methylglyoxal (MGO)-induced damages in terms of restored membrane deformability, reduced oxidative stress and eryptosis phenomenon. Antioxidant capacities of Ab extract on erythrocytes were retrieved in vivo in zebrafish previously infused with MGO. These results bring new evidences on the deleterious impacts of glycation on albumin and erythrocyte in diabetes. Furthermore, it reveals antioxidant and antiglycant properties of Ab that could be used for the dietary modulation of oxidative stress and glycation in hyperglycemic situations.

Risk of severe maternal morbidity or death in relation to elevated hemoglobin A1c preconception, and in early pregnancy: A population-based cohort study

BACKGROUND

The relation between prepregnancy average glucose concentration and a woman's risk of severe maternal morbidity (SMM) is unknown. The current study evaluated whether an elevated preconception hemoglobin A1c (A1c) is associated with SMM or maternal death among women with and without known prepregnancy diabetes mellitus (DM).

METHODS AND FINDINGS

A population-based cohort study was completed in Ontario, Canada, where there is universal healthcare. The main cohort included 31,225 women aged 16-50 years with a hospital live birth or stillbirth from 2007 to 2015, and who had an A1c measured within 90 days before conception, including 28,075 women (90%) without known prepregnancy DM. The main outcome was SMM or maternal mortality from 23 weeks' gestation up to 42 days postpartum. Relative risks (RRs) were generated using modified Poisson regression, adjusting for the main covariates of maternal age, multifetal pregnancy, world region of origin, and tobacco/drug dependence. The mean maternal age was 31.1 years. Overall, SMM or death arose among 682 births (2.2%). The RR of SMM or death was 1.16 (95% CI 1.14-1.19; p < 0.001) per 0.5% increase in A1c and 1.16 (95% CI 1.13-1.18; p < 0.001) after adjusting for the main covariates. The adjusted relative risk (aRR) was increased among those with (1.11, 95% CI 1.07-1.14; p < 0.001) and without (1.15, 95% CI 1.02-1.29; p < 0.001) known prepregnancy diabetes, and upon further adjusting for body mass index (BMI) (1.15, 95% CI 1.11-1.20; p < 0.001), or chronic hypertension and prepregnancy serum creatinine (1.11, 95% CI 1.04-1.18; p = 0.002). The aRR of SMM or death was 1.31 (95% CI 1.06-1.62; p = 0.01) in those with a preconception A1c of 5.8%-6.4%, and 2.84 (95% CI 2.31-3.49; p < 0.001) at an A1c > 6.4%, each relative to an A1c < 5.8%. Among those without previously recognized prepregnancy diabetes and whose A1c was >6.4%, the aRR of SMM or death was 3.25 (95% CI 1.76-6.00; p < 0.001). Study limitations include that selection bias may have incorporated less healthy women tested for A1c, and BMI was unknown for many women.

CONCLUSIONS

Our findings indicate that women with an elevated A1c preconception may be at higher risk of SMM or death in pregnancy or postpartum, including those without known prepregnancy DM.

On the Effect of Age-Dependent Mortality on the Stability of a System of Delay-Differential Equations Modeling Erythropoiesis

We present an age-structured model for erythropoiesis in which the mortality of mature cells is described empirically by a physiologically realistic probability distribution of survival times. Under some assumptions, the model can be transformed into a system of delay differential equations with both constant and distributed delays. The stability of the equilibrium of this system and possible Hopf bifurcations are described for a number of probability distributions. Physiological motivation and interpretation of our results are provided.

The Role of Circulating Cell-Free Hemoglobin in Sepsis-Associated Acute Kidney Injury

Sepsis is a heterogeneous clinical syndrome that is complicated commonly by acute kidney injury (sepsis-AKI). Currently, no approved pharmacologic therapies exist to either prevent sepsis-AKI or to treat sepsis-AKI once it occurs. A growing body of evidence supports a connection between red blood cell biology and sepsis-AKI. Increased levels of circulating cell-free hemoglobin (CFH) released from red blood cells during hemolysis are common during sepsis and can contribute to sepsis-AKI through several mechanisms including tubular obstruction, nitric oxide depletion, oxidative injury, and proinflammatory signaling. A number of potential pharmacologic therapies targeting CFH in sepsis have been identified including haptoglobin, hemopexin, and acetaminophen, and early phase clinical trials have suggested that acetaminophen may have beneficial effects on lipid peroxidation and kidney function in patients with sepsis. Bedside measurement of CFH levels may facilitate predictive enrichment for future clinical trials of CFH-targeted therapeutics. However, rapid and reliable bedside tests for plasma CFH will be required for such trials to move forward.

Effects of Quercetin Supplementation on Hematological Parameters in Non-Alcoholic Fatty Liver Disease: a Randomized, Double-Blind, Placebo-Controlled Pilot Study

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease which has become a public health concern. Since oxidative stress plays a crucial role in the pathogenesis of NAFLD, subsequent hematological disorders are expected. Therefore, antioxidant compounds such as quercetin could ameliorate the related side-effect of oxidative stress. The aim of the current study was to assess the effect of quercetin on hematological parameters in NAFLD patients. A randomized, double-blind, placebo-controlled trial was conducted as a pilot study. In this study 90 patients with NAFLD were supplemented with either a quercetin or a placebo capsule twice daily (500 mg) for 12 weeks. Blood sample was obtained for laboratory parameters at baseline and the end of week 12. End of trial values for red blood cell (RBC; p = 0.002), mean corpuscular hemoglobin concentration (p = 0.029), and mean platelet volume (p = 0.017), significantly increased and the levels of mean corpuscular volume (MCV; p = 0.023), RBC distribution width-coefficient of variation (p = 0.005), platelet distribution width (p = 0.015), and ferritin (p = 0.002) significantly decreased compared to the baseline in group receiving quercetin. Between group analysis revealed that RBC significantly increased (p = 0.025) but, mean corpuscular volume (p = 0.004), mean corpuscular hemoglobin (MCH; p = 0.002), and ferritin (p = 0.013) significantly decreased compared to placebo group. In this work quercetin showed significant effect on RBC, ferritin, MCV, and MCH in intervention group.

Recovery from repeated stressors: Physiology and behavior are affected on different timescales in house sparrows

For decades, researchers across disciplines have been captivated by classifying, diagnosing, and avoiding the consequences of chronic stress. Despite the vast body of literature this has generated, we still lack the ability to predict which individuals or populations may be susceptible to stress-related pathologies. One critical unanswered question is whether the impacts of repeated stressors are reversible, or if instead they permanently alter an individual. In this study, we exposed house sparrows (Passer domesticus) to 6 days of random, repeated stressors, permitted them 0, 1, 3, or 6 days to recover, and then assessed changes in their body mass, hypothalamic-pituitaryadrenal (HPA) axis (baseline, stress-induced corticosterone, negative feedback strength), immune function, uric acid concentrations, DNA damage levels, and perch hopping activity. Body mass did not vary between groups after recovery. We found that the HPA axis and perch hopping were not significantly impacted by the 6 days of stressors, but that uric acid and DNA damage increased. Short recovery periods tended to negatively affect the HPA axis and reduced uric acid levels, but these were reversed with longer recovery periods. Following the recovery periods, the birds experienced an additional 6 days of random stressors and their responses were assessed again. All recovery times reduced perch hopping and immune function, but paradoxically, DNA damage was highest in the birds that had the longest amount of time to recover. These results show that recovery time affects responses to subsequent chronic stress in complex ways, and highlight the importance of multimodal, interdisciplinary approaches to studying stress physiology.