Functional and immunological mapping of domains of the reticulocyte binding protein, Plasmodium vivax PvRBP2a.

We previously described a novel Plasmodium vivax invasion mechanism into human reticulocytes via the PvRBP2a-CD98 receptor-ligand pair. We assessed the PvRBP2a epitopes involved in CD98 binding and recognised by antibodies from infected patients using linear epitope mapping. We identified two epitope clusters mediating PvRBP2a-CD98 interaction. One cluster named cluster B (PvRBP2a431-448, TAALKEKGKLLANLYNKL) was the target of antibody responses in P. vivax-infected humans. Peptides from each cluster were able to prevent live parasite invasion of human reticulocytes. These results provide new insights for development of a malaria blood stage vaccine against P. vivax.

The Gárdos Channel and Piezo1 Revisited: Comparison between Reticulocytes and Mature Red Blood Cells.

The Gárdos channel (KCNN4) and Piezo1 are the best-known ion channels in the red blood cell (RBC) membrane. Nevertheless, the quantitative electrophysiological behavior of RBCs and its heterogeneity are still not completely understood. Here, we use state-of-the-art biochemical methods to probe for the abundance of the channels in RBCs. Furthermore, we utilize automated patch clamp, based on planar chips, to compare the activity of the two channels in reticulocytes and mature RBCs. In addition to this characterization, we performed membrane potential measurements to demonstrate the effect of channel activity and interplay on the RBC properties. Both the Gárdos channel and Piezo1, albeit their average copy number of activatable channels per cell is in the single-digit range, can be detected through transcriptome analysis of reticulocytes. Proteomics analysis of reticulocytes and mature RBCs could only detect Piezo1 but not the Gárdos channel. Furthermore, they can be reliably measured in the whole-cell configuration of the patch clamp method. While for the Gárdos channel, the activity in terms of ion currents is higher in reticulocytes compared to mature RBCs, for Piezo1, the tendency is the opposite. While the interplay between Piezo1 and Gárdos channel cannot be followed using the patch clamp measurements, it could be proved based on membrane potential measurements in populations of intact RBCs. We discuss the Gárdos channel and Piezo1 abundance, interdependencies and interactions in the context of their proposed physiological and pathophysiological functions, which are the passing of small constrictions, e.g., in the spleen, and their active participation in blood clot formation and thrombosis.

A comparative study of two routinely used protocols for ex vivo erythroid differentiation.

BACKGROUND: Erythropoiesis is a complex developmental process in which a hematopoietic stem cell undergoes serial divisions and differentiates through well-defined stages to give rise to red blood cells. Over the last decades, several protocols have been developed to perform ex vivo erythroid differentiation, allowing investigation into erythropoiesis and red cell production in health and disease. RESULTS: In the current study, we compared the two commonly used protocols by assessing the differentiation kinetics, synchronisation, and cellular yield, using molecular and cellular approaches. Peripheral blood CD34+ cells were cultured in a two-phase (2P) or a four-phase (4P) liquid culture (LC) and monitored for 20 days. Both protocols could recapitulate all stages of erythropoiesis and generate reticulocytes, although to different extents. Higher proliferation and viability rates were achieved in the 4P-LC, with a higher degree of terminal differentiation and enucleation, associated with higher levels of the erythroid-specific transcription factors GATA-1, KLF-1, and TAL-1. Although the 2P-LC protocol was less efficient regarding terminal erythroid differentiation and maturation, it showed a higher yield of erythroid progenitors in the erythropoietin (EPO)-free expansion phase. CONCLUSIONS: We provide data supporting the use of one protocol or the other to study the biological processes occurring in the early or late stages of erythroid differentiation, depending on the physiological process or pathological defect under investigation in a given study.

The Immature Reticulocyte Fraction (IRF) in the Sysmex XN-1000V Analyzer Can Differentiate between Causes of Regenerative and Non-Regenerative Anemia in Dogs and Cats.

The Sysmex XN-1000V analyzer can identify those reticulocytes with high RNA content and fluorescence, providing the immature reticulocyte fraction (IRF). While this parameter has been used in human medicine to identify the cause of anemia, few studies have focused on its use in veterinary medicine. In this study, we determined the IRF and related reticulocyte parameters in a large population of non-anemic and anemic dogs and cats (subclassified depending on the origin of their anemia). The IRF was significantly higher in hemolytic anemias compared to hemorrhagic ones in both species. Moreover, the IRF was significantly lower in dogs and cats with bone marrow failure than in other non-regenerative anemias and in both groups compared to pre-regenerative anemias. The accurate cut-off values for the differential in regenerative anemias and reference ranges for both species using the Sysmex XN-1000V are also reported. The measurement of the IRF in this analyzer can help clinicians to further classify the type of anemia in both species.

Usefulness of baseline immature reticulocyte fraction to mature reticulocyte fraction ratio (IMR) as A prognostic predictor for patients with small cell lung cancer.

Background: Small cell lung cancer (SCLC) has a strong invasive ability and a high degree of malignancy, so accurate prognosis prediction is crucial for making the most favorable treatment decision.Unfortunately, there is a scarcity of prognostic indicators specific to SCLC. Reticulocyte levels in blood parameters have been linked to the prognosis of various malignancies. Given SCLC's aggressive characteristics, identifying reliable prognostic markers, such as reticulocyte counts, becomes pivotal in enhancing prognostic accuracy and guiding effective therapeutic strategies. Objective: This study aimed to evaluate the predictive power of the immature reticulocyte fraction (IRF) to mature reticulocyte fraction (MRF) ratio (IMR) for survival outcomes in patients with SCLC. Materials and methods: A retrospective analysis was conducted on 192 patients with small cell lung cancer (SCLC). The median values of various prognostic indicators, such as IMR, IRF, MRF, reticulocyte count (RET), SII (systemic immune-inflammatory index), were utilized as cutoff points, categorizing patients into high and low groups. The Kaplan-Meier method, univariate, multivariate analyses Cox regression, and C-index were used to analyze the prognostic factors for overall survival (OS). Results: In our cohort, 138 (71.9 %) were male, 119 (62 %) were smokers, and 82 (57.3 %) were older than 60 years old. The median survival time was 18.15 months.Higher mortality was observed in the high IMR and high IRF groups, while the high MRF group exhibited lower mortality. At the same time, mortality was lower in the high MRF group. Univariate analysis showed that smoking history (P = 0.006), tumor stage (P = 0.002), chemotherapy cycle (P = 0.014), IMR (P = 0.01), and many other factors significantly affected the prognosis of SCLC. Multivariate analysis demonstrated that elevated IMR was an independent adverse predictor of OS (P = 0.039, HR = 0.330). Spearman test confirmed that the prognostic indicators IRF, IMR, and SII were positively correlated with the overall survival rate of patients with SCLC. Kaplan-Meier analysis showed that the OS rate of patients with high IMR was significantly worse (P = 0.0096). In addition, we found that IMR was superior to IRF in distinguishing patients with different outcomes in the low and high groups (P < 0.05). Our novel integration index, combining IMR with the TNM stage system and SII index, exhibited superior prognostic value compared to the original index. Additionally, the combination of prognostic indicators IMR and SII significantly stratified stage I-II SCLC patients (P ＜0.05). Conclusions: The prognostic index based on peripheral blood IMR stands out as an independent predictor for SCLC patients pre-treatment. Its accessibility through routine blood analysis facilitates immediate clinical application without requiring prolonged scientific research validation. The integration of IMR with the TNM score enhances survival prediction and risk stratification. Notably, when combined with the SII score, the new IMR index demonstrates significant improvements in prognostication for stage I-II small cell lung cancer.

Genetic diversity and natural selection of Plasmodium vivax reticulocyte invasion genes in Ecuador.

BACKGROUND: Knowledge of the diversity of invasion ligands in malaria parasites in endemic regions is essential to understand how natural selection influences genetic diversity of these ligands and their feasibility as possible targets for future vaccine development. In this study the diversity of four genes for merozoite invasion ligands was studied in Ecuadorian isolates of Plasmodium vivax. METHODS: Eighty-eight samples from P. vivax infected individuals from the Coast and Amazon region of Ecuador were obtained between 2012 and 2015. The merozoite invasion genes pvmsp-1-19, pvdbpII, pvrbp1a-2 and pvama1 were amplified, sequenced, and compared to the Sal-1 strain. Polymorphisms were mapped and genetic relationships between haplotypes were determined. RESULTS: Only one nonsynonymous polymorphism was detected in pvmsp-1-19, while 44 nonsynonymous polymorphisms were detected in pvdbpII, 56 in pvrbp1a-2 and 33 in pvama1. While haplotypes appeared to be more related within each area of study and there was less relationship between parasites of the coastal and Amazon regions of the country, diversification processes were observed in the two Amazon regions. The highest haplotypic diversity for most genes occurred in the East Amazon of the country. The high diversity observed in Ecuadorian samples is closer to Brazilian and Venezuelan isolates, but lower than reported in other endemic regions. In addition, departure from neutrality was observed in Ecuadorian pvama1. Polymorphisms for pvdbpII and pvama1 were associated to B-cell epitopes. CONCLUSIONS: pvdbpII and pvama1 genetic diversity found in Ecuadorian P. vivax was very similar to that encountered in other malaria endemic countries with varying transmission levels and segregated by geographic region. The highest diversity of P. vivax invasion genes in Ecuador was found in the Amazonian region. Although selection appeared to have small effect on pvdbpII and pvrbp1a-2, pvama1 was influenced by significant balancing selection.

Associations of obesity and body shape with erythrocyte and reticulocyte parameters in the UK Biobank cohort.

BACKGROUND: Obesity is associated with type 2 diabetes mellitus and chronic low-grade inflammation. Although chronic inflammatory conditions and diabetes are associated with anaemia, less is known about associations of obesity and body shape, independent of each other, with erythrocyte and reticulocyte parameters. METHODS: We investigated the associations of body mass index (BMI) and the allometric body shape index (ABSI) and hip index (HI), which are uncorrelated with BMI, with erythrocyte and reticulocyte parameters (all continuous, on a standard deviation (SD) scale) in UK Biobank participants without known metabolic, endocrine, or major inflammatory conditions (glycated haemoglobin HbA1c < 48 mmol/mol, C-reactive protein CRP < 10 mg/L). We examined erythrocyte count, total reticulocyte count and percent, immature reticulocyte count and fraction (IRF), haemoglobin, haematocrit, mean corpuscular haemoglobin mass (MCH) and concentration (MCHC), mean corpuscular and reticulocyte volumes (MCV, MRV), and red cell distribution width (RDW) in multivariable linear regression models. We additionally defined body shape phenotypes with dichotomised ABSI (≥ 73 women; ≥ 80 men) and HI (≥ 64 women; ≥ 49 men), including "pear" (small-ABSI-large-HI) and "apple" (large-ABSI-small-HI), and examined these in groups according to BMI (18.5-25 normal weight; 25-30 overweight; 30-45 kg/m2 obese). RESULTS: In 105,853 women and 100,854 men, BMI and ABSI were associated positively with haemoglobin, haematocrit, and erythrocyte count, and more strongly with total reticulocyte count and percent, immature reticulocyte count and IRF. HI was associated inversely with all, but least with IRF. Associations were comparable in women and men. In groups according to obesity and body shape, erythrocyte count was ~ 0.6 SD higher for obese-"apple" compared to normal-weight-"pear" phenotype (SD = 0.31*1012/L women, SD = 0.34*1012/L men), total reticulocyte count was ~ 1.1 SD higher (SD = 21.1*109/L women, SD = 23.6*109/L men), immature reticulocyte count was ~ 1.2 SD higher (SD = 7.9*109/L women, SD = 8.8*109/L men), total reticulocyte percent was ~ 1.0 SD higher (SD = 0.48% women and men), and IFR was over 0.7 SD higher (SD = 5.7% women and men). BMI but not ABSI or HI was associated more weakly inversely with MCV, MRV, and MCH, but positively with MCHC in men and RDW in women. CONCLUSIONS: In obesity uncomplicated with diabetes, larger BMI and ABSI are associated with increased erythropoiesis and reticulocyte immaturity.

Accessory-cell-free differentiation of hematopoietic stem and progenitor cells into mature red blood cells.

BACKGROUND AIMS: The culture and ex vivo engineering of red blood cells (RBCs) can help characterize genetic variants, model diseases, and may eventually spur the development of applications in transfusion medicine. In the last decade, improvements to the in vitro production of RBCs have enabled efficient erythroid progenitor proliferation and high enucleation levels from several sources of hematopoietic stem and progenitor cells (HSPCs). Despite these advances, there remains a need for refining the terminal step of in vitro human erythropoiesis, i.e., the terminal maturation of reticulocytes into erythrocytes, so that it can occur without feeder or accessory cells and animal-derived components. METHODS: Here, we describe the near-complete erythroid differentiation of cultured RBCs (cRBCs) from adult HSPCs in accessory-cell-free and xeno-free conditions. RESULTS: The approach improves post-enucleation cell integrity and cell survival, and it enables subsequent storage of cRBCs for up to 42 days in classical additive solution conditions without any specialized equipment. CONCLUSIONS: We foresee that these improvements will facilitate the characterization of RBCs derived from gene-edited HSPCs.

Relación del equivalente de hemoglobina reticulocitaria (Ret-He) con diferentes categorías según la concentración de hemoglobina en candidatos a donar sangre

Objetivo: determinar la relación entre el Ret-He con diferentes categorías según la concentración de hemoglobina en candidatos a donar sangre. Materiales y Métodos: Se realizó un estudio transversal a partir de la revisión de 227 historias clínicas de candidatos a donar sangre durante el mes de diciembre del 2021 en el Servicio de Banco de Sangre y Hemoterapia del Hospital Cayetano Heredia. Se categorizó en 3 grupos según los niveles de hemoglobina: Grupo 1: ≥12,5 g/dl (mujeres) - ≥13,5 g/dl (varones). Grupo 2: 12 g/dl ≥ mujeres <12.5 g/dl y 13 g/dl ≥ varones<13.5 g/dl. Grupo 3: <12 g/dl (mujeres) - <13 g/dl (varones). Se tomaron datos de hematocrito, hemoglobina, VCM, HCM, CHCM y Ret-He. Para el análisis bivariado se utilizó el análisis de varianza (ANOVA) y se consideró un nivel de significancia del 5 %. Resultados: La mediana de Ret-He fue mayor en el grupo 1 que en el grupo 2 (33.5 frente a 32.5; p=0.002) y en el grupo 3 (33.5 frente a 27.8; p<0.001). Se encontró relación estadísticamente significativa entre los grupos estudiados y Ret-He (p<0.001), además de una correlación positiva moderada fuerte entre Ret-He y los índices eritrocitarios. Conclusiones: Se encontró una asociación significativa entre los grupos basados en categorías de hemoglobina y la Ret-He en candidatos a donar sangre.

Objective: to determine the relationship between Ret-He with different categories according to hemoglobin concentration in candidates for blood donation. Methods: A cross-sectional study was carried out based on the review of 227 medical records of candidates to donate blood during the month of December 2021 in the Blood Bank and Hemotherapy Service of the Cayetano Heredia Hospital. They were categorized into 3 groups according to hemoglobin levels: Group 1: ≥12.5 g/dl (females) - ≥13.5 g/dl (males). Group 2: 12 g/dl ≥ females <12.5 g/dl and 13 g/dl ≥ males<13.5 g/dl. Group 3: <12 g/dl (females) - <13 g/dl (males). Hematocrit, hemoglobin, VCM, HCM, CHCM and Ret-He data were collected. For the bivariate analysis, analysis of variance (ANOVA) was used and a significance level of 5% was considered. Results: The median Ret-He was higher in group 1 than in group 2 (33.5 vs. 32.5; p=0.002) and in group 3 (33.5 vs. 27.8; p<0.001). A statistically significant relationship was found between the groups studied and Ret-He (p<0.001), in addition to a moderate-strong positive correlation between Ret-He and erythrocyte indices. Conclusions: An association was found between groups based on hemoglobin categories and Ret-He in blood donation candidates.

Immunological impact of the CD71+ RBCs: A potential immune mediator in transfusion.

Donor - recipient sex - mismatched transfusion is associated with increased mortality. The mechanisms for this are not clear, but it may relate to transfusion-related immunomodulation. Recently, CD71+ erythroid cells (CECs), including reticulocytes (CD71+ RBCs) and erythroblasts, have been identified as potent immunoregulatory cells. The proportion of CD71+ RBCs in the peripheral blood is sufficient to play a potential immunomodulatory role. Differences in the quantity of CD71+ RBCs are dependent on blood donor sex. The total number of CD71+ RBCs in red cell concentrates is also affected by blood manufacturing methods, and storage duration. As a component of the total CECs, CD71+ RBCs can affect innate and adaptive immune cells. Phagocytosed CECs directly reduce TNF-α production from macrophages. CECs can also suppress the production of TNF-α production from antigen presenting cells. Moreover, CECs can suppress T cell proliferation thorough immune mediation and / or direct cell-to-cell interactions. Different in their biophysical features compared to mature RBCs, blood donor CD71+ RBCs may be preferential targets for the macrophages. This report summarizes the currently literature supporting an important role for CD71+ RBCs in adverse transfusion reactions including immune mediation and sepsis.

Bone marrow iron scoring in healthy and clinically ill dogs with and without evidence of iron-restricted erythropoiesis.

BACKGROUND: There are few reports in dogs that have evaluated the utility of semi-quantitative scoring of bone marrow iron stores in conjunction with reticulocyte hemoglobin (CHr) to identify iron-restricted erythropoiesis due to absolute iron deficiency or iron sequestration. OBJECTIVES: An established system for scoring iron stores in human bone marrow samples was applied to dogs. The objectives were to evaluate interobserver agreement (Κω ), determine marrow iron scores in dogs without detectable hematologic abnormalities, and assess combined interpretation of iron scores and CHr to evaluate for iron-restricted erythropoiesis. METHODS: Four blinded observers independently scored iron in 139 Prussian blue-stained canine marrow samples from 0 (none) to 6 (very heavy), including healthy controls (n = 12), clinically ill dogs with (n = 100) and without (n = 16) detectable hematologic abnormalities, and dogs with experimental nutritional iron deficiency (n = 11). Additional medical record data were available for 118 dogs to evaluate for other evidence of iron deficiency (abnormal CHr, RBC indices, serum iron variables, external blood loss, or nutritional deficiencies). RESULTS: Mean Κω was 0.69 (substantial agreement) for all samples but was 0.44 (moderate agreement) for samples with iron scores <3, indicating distinguishing scores 0-2 may not be reliable. Dogs without detectable hematologic abnormalities had scores from 3-5. Dogs with scores <3 and decreased CHr often had more indicators of iron deficiency vs dogs only having low iron scores or low CHr. CONCLUSIONS: Evaluation of dogs with marrow iron score <3 for external blood loss or nutritional deficiencies is likely clinically worthwhile, particularly if there is also decreased CHr.

Culture and transfection: Two major bottlenecks in understanding Plasmodium vivax biology.

The long term in vitro culture of Plasmodium falciparum was successfully established by Trager and Jensen in 1976; however it largely remains unachieved for P. vivax. The major obstacle associated with Plasmodium vivax in vitro culture is its predilection for invading younger reticulocytes and the complex remodelling of invaded reticulocytes. There are many factors under exploration for this predilection and host-parasite interactions between merozoites and invaded reticulocytes. These include various factors related to parasite, host and environment such as compromised reticulocyte osmotic stability after invasion, abundance of iron in the reticulocytes which makes them favourable for P. vivax growth and propagation and role of a hypoxic environment in P. vivax in vitro growth. P. vivax blood stage transfection represents another major hurdle towards understanding this parasite's complex biology. Efforts in making this parasite amenable for molecular investigation by genetic modification are limited. Newer approaches in sustaining a longer in vitro culture and thereby help advancing transfection technologies in P. vivax are urgently needed that can be explored to understand the unique biology of this parasite.

Cultured CD71+ erythroid cells modulate the host immune response.

OBJECTIVE: The study aimed to determine the impact of Red Blood Cells (RBCs) generated from peripheral blood mononuclear cells (PBMCs) on T cell proliferation and host response following whole blood stimulation. BACKGROUND: Culturing RBCs is a potential solution for donor shortage. The impact of immature cultured RBCs which express CD71+ on host immune response is not known. METHODS/MATERIALS: PBMCs were seeded in an erythroid expansion medium. CD71+ cells were isolated at days 14 and 21 of culture and incubated with either purified T cells or with LPS-stimulated whole blood. Controls were incubated with medium. RESULTS: At day 9, the percentage of cells that expressed CD45 and CD71 reached to the highest level (32.9%, IQR; 26.2-39.05) while the percentage of cells that expressed CD71 and CD235a reached to the highest level on day 17 (70.2%, IQR; 66.1-72.8). Incubation of T cells with days 14 CD71+ cells and day 21 CD71+ cells increased T cell proliferation. In a whole blood stimulation assay, day 21 CD71+ cells, but not day 14 CD71+ cells, inhibited the production of IL-6 and TNFα. CONCLUSION: Cultured erythroid cells can modulate the immune response by promoting T cell proliferation and inhibiting cytokine secretions following whole blood stimulation.

Evaluation of RET-He values as an early indicator of iron deficiency anemia in pregnant women

Abstract Introduction During pregnancy, women are at an increased risk of developing iron-deficiency anemia. Objective The objective of this study was to assess the diagnostic performance of the reticulocyte hemoglobin equivalent (RET-He) in the early detection of iron-deficiency anemia in a group of pregnant women and to establish a reference range for this parameter in a group of control individuals. Method: A total of 60 patients and 130 control subjects were included in the study. Blood samples collected from the subjects were submitted to a complete blood count and a serum ferritin test and the data were analyzed by comparing the groups and ROC curves. Results The reference range found for the RET-He was between 29.75pg and 38.24pg, with a median of 35pg. The receiver operating characteristic (ROC) curve analysis for the ferritin parameter showed an area under the curve of 0.732 for the RET-He, 0.586 for hemoglobin, 0.551 for the mean corpuscular hemoglobin concentration and 0.482 for the mean corpuscular volume. Conclusion Early diagnosis of iron deficiency anemia in pregnancy is essential to prevent damage to both maternal and fetal health. The RET-He presents an excellent potential as an auxiliary tool for the diagnosis of iron deficiency in pregnant women.

Clinical utility of immature reticulocyte fraction for identifying early red blood cell regeneration in anemic dogs.

BACKGROUND: Evaluating regeneration is essential for the classification and differential diagnosis of anemia in dogs. Early detection of regeneration is challenging in anemic dogs. OBJECTIVES: This study assessed the value of immature reticulocyte fraction (IRF) in differentiating preregenerative anemia (PRA) from nonregenerative anemia (NRA) in dogs. ANIMALS: Ninety-four dogs: 49 controls and 45 with anemia. METHODS: Case-control study. Fractions of low-, medium- (MFR), and high-fluorescence reticulocytes (HFR), were measured using the ADVIA 2120i hematology analyzer. The IRF was calculated as the sum of percentages of MFR and HFR. Data from dogs with regenerative anemia (RA, n = 19), PRA (n = 11), and NRA (n = 15) were retrospectively analyzed. The value of IRF was compared with reticulocyte production index (RPI) using the receiver operating characteristic (ROC) curve. RESULTS: The median of IRF was significantly higher in dogs with RA (46.5%; range, 40.9-53.6%; P < .001) and PRA (40.6%; range, 27.7-47.1%; P = .01) than in controls (22.1%; range, 16.9-29.3%). The IRF in dogs with PRA showed no difference compared to dogs with RA (P > .99) but was higher than dogs with NRA (18.7%; range, 8.8-24%; P = .00). The area under the ROC curve of IRF was superior to that of RPI (0.897 vs 0.818, P = .00) in differentiating dogs with PRA from NRA. CONCLUSIONS AND CLINICAL IMPORTANCE: The IRF is a reliable variable for detecting early regeneration in anemic dogs without reticulocytosis. The study suggests that the measurement of IRF could be useful in classifying anemic dogs.

Interplay between liver and blood stages of Plasmodium infection dictates malaria severity via γδ T cells and IL-17-promoted stress erythropoiesis.

Plasmodium replicates within the liver prior to reaching the bloodstream and infecting red blood cells. Because clinical manifestations of malaria only arise during the blood stage of infection, a perception exists that liver infection does not impact disease pathology. By developing a murine model where the liver and blood stages of infection are uncoupled, we showed that the integration of signals from both stages dictated mortality outcomes. This dichotomy relied on liver stage-dependent activation of Vγ4+ γδ T cells. Subsequent blood stage parasite loads dictated their cytokine profiles, where low parasite loads preferentially expanded IL-17-producing γδ T cells. IL-17 drove extra-medullary erythropoiesis and concomitant reticulocytosis, which protected mice from lethal experimental cerebral malaria (ECM). Adoptive transfer of erythroid precursors could rescue mice from ECM. Modeling of γδ T cell dynamics suggests that this protective mechanism may be key for the establishment of naturally acquired malaria immunity among frequently exposed individuals.

T-cell cellular stress and reticulocyte signatures, but not loss of naïve T lymphocytes, characterize severe COVID-19 in older adults.

In children and younger adults up to 39 years of age, SARS-CoV-2 usually elicits mild symptoms that resemble the common cold. Disease severity increases with age starting at 30 and reaches astounding mortality rates that are ~330 fold higher in persons above 85 years of age compared to those 18-39 years old. To understand age-specific immune pathobiology of COVID-19, we have analyzed soluble mediators, cellular phenotypes, and transcriptome from over 80 COVID-19 patients of varying ages and disease severity, carefully controlling for age as a variable. We found that reticulocyte numbers and peripheral blood transcriptional signatures robustly correlated with disease severity. By contrast, decreased numbers and proportion of naïve T-cells, reported previously as a COVID-19 severity risk factor, were found to be general features of aging and not of COVID-19 severity, as they readily occurred in older participants experiencing only mild or no disease at all. Single-cell transcriptional signatures across age and severity groups showed that severe but not moderate/mild COVID-19 causes cell stress response in different T-cell populations, and some of that stress was unique to old severe participants, suggesting that in severe disease of older adults, these defenders of the organism may be disabled from performing immune protection. These findings shed new light on interactions between age and disease severity in COVID-19.

Evaluation of RET-He values as an early indicator of iron deficiency anemia in pregnant women.

INTRODUCTION: During pregnancy, women are at an increased risk of developing iron-deficiency anemia. OBJECTIVE: The objective of this study was to assess the diagnostic performance of the reticulocyte hemoglobin equivalent (RET-He) in the early detection of iron-deficiency anemia in a group of pregnant women and to establish a reference range for this parameter in a group of control individuals. METHOD: A total of 60 patients and 130 control subjects were included in the study. Blood samples collected from the subjects were submitted to a complete blood count and a serum ferritin test and the data were analyzed by comparing the groups and ROC curves. RESULTS: The reference range found for the RET-He was between 29.75pg and 38.24pg, with a median of 35pg. The receiver operating characteristic (ROC) curve analysis for the ferritin parameter showed an area under the curve of 0.732 for the RET-He, 0.586 for hemoglobin, 0.551 for the mean corpuscular hemoglobin concentration and 0.482 for the mean corpuscular volume. CONCLUSION: Early diagnosis of iron deficiency anemia in pregnancy is essential to prevent damage to both maternal and fetal health. The RET-He presents an excellent potential as an auxiliary tool for the diagnosis of iron deficiency in pregnant women.

Potential value of differential expression of CDC42 gene in adult and umbilical cord blood reticulocytes / 中国输血杂志

【Objective】 To explore critical regulatory genes in the hemoglobin switch process by analyzing transcriptomic data from the GSE6236, GSE17639 and GSE35102 datasets. 【Methods】 The mRNA expression profiles of the three datasets were downloaded from the GEO database and gene annotation was performed using the AnnoProbe package.The remove-BatchEffect function of the Limma package was used to remove batch effects. Weighted gene co-expression network analysis (WGCNA) was used to explore the most relevant modular genes in reticulocytes. The receiver operating characteristic curve (ROC) was used to assess the value of differential genes in differentiating between cord blood and adult peripheral blood reticulocytes. The GSE35102 dataset was used to validate changes in differential gene expression during hemoglobin transformation. Finally, real-time quantitative PCR was used to verify differential gene expression in cord blood and adult peripheral blood reticulocytes. 【Results】 Twelve genes showed differential expression in reticulocytes from cord blood and adult peripheral blood ( |logFC|≥1.5, P<0.05). WGCNA found that genes in the blue module were most strongly associated with reticulocytes (R2 =0.76,P<0.001). Of the five genes that overlapped between the two, only CDC42 showed differential expression in the combined dataset (t =3.776, P<0.001) and was able to better differentiate between reticulocytes in cord blood and adult peripheral blood. The expression of CDC42 varied significantly during the hemoglobin transformation process (Z = -2.908, P<0.01), and was significantly lower in adult reticulocytes compared to reticulocytes from cord blood (t =7.824, P <0.001). 【Conclusion】 The CDC42 gene is involved in the hemoglobin switching of reticulocytes and could be a potential therapeutic target for sickle cell disease.

Maternal diabetes and the role of neonatal reticulocyte hemoglobin content as a biomarker of iron status in the perinatal period.

Aims: We aimed to evaluate the effects of maternal diabetes on neonatal iron status, measuring erythrocyte indices including hemoglobin, hematocrit, reticulocytes, mean corpuscular volume (MCV), percent (%) hypochromia, ferritin, and additionally mean reticulocyte hemoglobin content (MCHr) as an early marker of iron deficiency, and examine the association between neonatal MCHr, red cell indices, and ferritin. Materials and Methods: We conducted a hospital-based prospective cohort study in a tertiary neonatal unit of a University Hospital from 2018 to 2020. We enrolled 126 maternal-infant pairs of mothers whose pregnancy was associated with diabetes and 74 maternal-infant pairs from uncomplicated pregnancies. Erythrocyte indices were analyzed within the first twelve hours after birth. Erythrocyte parameters were compared between infants of the diabetes and the non-diabetic group. We examined the correlation of the neonatal MCHr with perinatal characteristics, including gestation, birth weight, maternal body mass index, the erythrocytic indices, maternal diabetes, maternal obesity, prematurity, small-for-gestational-age status, maternal preeclampsia, and maternal anemia. Finally, we evaluated the discordance between neonatal MCHr and neonatal ferritin. Results: Infants of the diabetes group had a significantly lower MCHr (32.6 pg vs. 34.2 pg, p=0.003) compared with infants of uncomplicated pregnancies. Neonatal MCHr was significantly correlated with maternal hypochromia (r=-0.237, p=0.004) and neonatal MCV (r=0.674, p<0.001). Neonatal MCHr was significantly associated with maternal diabetes [standardized coefficients 0.21, 95% confidence interval (CI) 0.05-0.58, p=0.003) and maternal preeclampsia (standardized coefficients 0.17, 95% CI 0.02-0.92, p=0.019), after adjusting for maternal anemia, maternal obesity, prematurity, and small-for-gestational-age status. Those results were consistent also when analyzing maternal-infant pairs with pre-existing diabetes, and maternal-infant pairs with gestational diabetes. There was significant discordance between neonatal MCHr and neonatal ferritin (p=0.001). Conclusions: MCHr was significantly lower in infants of mothers whose pregnancy was associated with diabetes compared with infants of non-diabetic mothers and correlated with neonatal and maternal red cell indices of iron deficiency. Since there was significant discordance between neonatal MCHr and ferritin during the first postnatal day, it is possible that MCHr could be used as a screening test for iron deficiency, especially in infants.