Transferrin Receptor is Associated with Sensitivity to Ferroptosis Inducers in Hepatocellular Carcinoma.

PURPOSE: Transferrin receptor (TFR), a membrane protein that has a critical role in the transport of iron into cells, is known to be a ferroptosis-related marker. Although TFR is reported to be abundantly expressed in tumor cells, its relationship with ferroptosis inducers in hepatocellular carcinoma (HCC) remains unclear. METHODS: The authors performed immunohistochemical staining of TFR and divided 350 HCC patients into two groups according to its expression. They analyzed the association between TFR expression and prognosis or clinicopathologic factors. In addition, the regulation of malignant activity and its effect on the efficacy of ferroptosis inducers were investigated in vitro. RESULTS: For this study, 350 patients were divided into TFR-positive (n =180, 51.4%) and TFR-negative (n = 170, 48.6%) groups. The TFR-positive group had more hepatitis B surface antigen (HBs-Ag) (p = 0.0230), higher α-fetoprotein (AFP) levels (p = 0.0023), higher des-gamma-carboxyprothrombin (DCP) levels (p = 0.0327), a larger tumor size (p = 0.0090), greater proportions of Barcelona Clinic Liver Cancer (BCLC) stage B or C (p = 0.0005), poor differentiation (p < 0.0001), and microscopic intrahepatic metastasis (p = 0.0066). In the multivariate analyses, TFR expression was an independent prognostic factor in disease-free survival (p = 0.0315). In vitro, TFRC knockdown decreased cell motility. In addition, TFRC knockdown abolished artesunate (AS)-, lenvatinib-, and sorafenib-induced ferroptosis in HCC cell lines. The study demonstrated that simultaneous treatment of AS with multi-kinase inhibitor augmented the ferroptosis-inducing effects of AS in HCC cell lines. CONCLUSION: TFR expression is a poor prognostic factor in HCC, but its expression increases sensitivity to ferroptosis-inducing agents.

Sex Matters: Physiological Abundance of Immuno-Regulatory CD71+ Erythroid Cells Impair Immunity in Females.

Mature erythrocytes are the major metabolic regulators by transporting oxygen throughout the body. However, their precursors and progenitors defined as CD71+ Erythroid Cells (CECs) exhibit a wide range of immunomodulatory properties. Here, we uncover pronounced sexual dimorphism in CECs. We found female but not male mice, both BALB/c and C57BL/6, and human females were enriched with CECs. CECs, mainly their progenitors defined as CD45+CECs expressed higher levels of reactive oxygen species (ROS), PDL-1, VISTA, Arginase II and Arginase I compared to their CD45- counterparts. Consequently, CECs by the depletion of L-arginine suppress T cell activation and proliferation. Expansion of CECs in anemic mice and also post-menstrual cycle in women can result in L-arginine depletion in different microenvironments in vivo (e.g. spleen) resulting in T cell suppression. As proof of concept, we found that anemic female mice and mice adoptively transferred with CECs from anemic mice became more susceptible to Bordetella pertussis infection. These observations highlight the role of sex and anemia-mediated immune suppression in females. Notably, enriched CD45+CECs may explain their higher immunosuppressive properties in female BALB/c mice. Finally, we observed significantly more splenic central macrophages in female mice, which can explain greater extramedullary erythropoiesis and subsequently abundance of CECs in the periphery. Thus, sex-specific differences frequency in the frequency of CECs might be imprinted by differential erythropoiesis niches and hormone-dependent manner.

Flow cytometric expression of CD71, CD81, CD44 and CD39 in B cell lymphoma.

Flow cytometry is a useful ancillary tool for the diagnosis of nodal B cell lymphomas. Well-established antigens have diagnostic limitations. This study aimed to assess the expression of CD71, CD81, CD44 and CD39 by flow cytometry in B cell lymphomas. Expression of these 4 antigens was queried in 185 samples with a diagnosis of a B cell lymphoma according to a histological examination of the lymph node and the World Health Organization (WHO) classification (follicular lymphoma [FL, n = 96], diffuse large B cell lymphoma/High grade B cell lymphoma [DLBCL/HGBH, n = 48], marginal zone lymphoma/lymphoplasmacytic lymphoma [MZL/LPL, n = 14], chronic lymphocytic leukemia/small lymphocytic lymphoma [CLL, n = 10], mantle cell lymphoma [MCL, n = 11], Burkitt lymphoma [BL, n = 4] and other [n = 2]). CD81 was bright and CD44 was dim in germinal center-derived malignancies, particularly aggressive lymphomas (BL and CD10-positive DLBCL/HGBL). CD81 was very dim in CLL. CD71 was bright in aggressive lymphomas (DLBCL/HGBL and BL). CD39 was bright in CD10-negative DLBCL. CD71 appeared valuable in the differential diagnosis between indolent and aggressive lymphomas, CD39 between CD10-negative DLBCL and MZL/LPL and CD81 between MCL and CLL. To conclude, we report the expression of CD71, CD81, CD44 and CD39 by FC in B cell lymphomas. Further studies will have to determine the value they add to specific FC panels.

High erythroferrone expression in CD71+ erythroid progenitors predicts superior survival in myelodysplastic syndromes.

Ineffective erythropoiesis and iron overload are common in myelodysplastic syndromes (MDS). Erythroferrone (ERFE) and growth/differentiation factor 15 (GDF15) are two regulators of iron homeostasis produced by erythroid progenitors. Elevated systemic levels of ERFE and GDF15 in MDS are associated with dysregulated iron metabolism and iron overload, which is especially pronounced in MDS with SF3B1 gene mutations. However, the role of ERFE and GDF15 in MDS pathogenesis and their influence on disease progression are largely unknown. Here, we analyzed the expression of ERFE and GDF15 in CD71+ erythroid progenitors of n = 111 MDS patients and assessed their effects on patient survival. The expression of ERFE and GDF15 in MDS was highly aberrant. Unexpectedly, ERFE expression in erythroprogenitors was highly relevant for MDS prognosis and independent of International Prognostic Scoring System (IPSS) stratification. Although ERFE expression was increased in patients with SF3B1 mutations, it predicted overall survival (OS) in both the SF3B1wt and SF3B1mut subgroups. Of note, ERFE overexpression predicted superior OS in the IPSS low/Int-1 subgroup and in patients with normal karyotype. Similar observations were made for GDF15, albeit not reaching statistical significance. In summary, our results revealed a strong association between ERFE expression and MDS outcome, suggesting a possible involvement of ERFE in molecular MDS pathogenesis.

Soluble Transferrin Receptor (sTfR) Identifies Iron Deficiency Anemia (IDA) in Pulmonary Tuberculosis Patients.

BACKGROUND: iron deficiency in pulmonary tuberculosis (TB) patients may weaken their immune system, causing difficulty in overcoming the infection. Accurate diagnosis of iron deficiency anemia (IDA) in pulmonary TB patients is essential. In order to prove the iron deficient state, diagnosis should focus on inflammatory factors, which could highly affect the outcome of iron status, such as measurement of serum ferritin (SF). Soluble Transferrin Receptor (sTfR) is the best parameter to diagnose iron deficiency in the inflammatory condition. This study aimed to understand the role of sTfR to identify IDA in TB patients. METHODS: cross-sectional study were applied to 3 study groups: anemic pulmonary TB (68 subjects), IDA (7 subjects), and non-anemic pulmonary TB (15 subjects). The test averages and correlations between sTfR, SF, and other hematological parameters were measured and analyzed. RESULTS: significant differences of sTfR were found in the anemic TB group compared to the IDA group and also between the IDA and non-anemic TB groups (p<0.0001). However, there was no significant difference (p>0.05) between TB anemic and non-anemic groups. We also found no significant difference between the TB anemic sub-group with normal levels of sTfR compared with the non-anemic group. There was no significant difference of sTfR levels between sub-group of increasing sTfR and group IDA (p>0.05). However, there was strong correlation between sTfR and SF in the IDA group (r=-0.89; p=0.007). CONCLUSION: the findings suggest verifying the sTfR amount in anemic patients with pulmonary TB suffering from inflammation, so that the iron deficiency could be more accurately identified and properly treated.

Phenotype changes of oral epithelial stem cells after in vitro culture.

The aim of our study was to isolate populations of keratinocyte stem cells based on the expression of cell surface markers and to investigate whether the culture could affect their phenotype. keratinocytes from human oral mucosa were sorted based on the expression of the epithelial stem cell markers p75NTR and CD71. We also examined the co-expression of other epithelial stem markers such as integrins ß1 and α6 and their stem cell-like proprieties in in vitro assays. Three passages after being sorted by MACS, more than 93% of the p75NTR+ve cells lost the expression of p75NTR, while 5.46% of the p75NTR-ve gained it. Within the small population of the p75NTR+ve cells, 88% co-expressed other epithelial stem cell markers such as integrins ß1 and α6, while only 28% of p75NTR-ve cells co-expressed these markers. These results were confirmed by sorting cells by FACS. Additionally, when double staining was used for sorting cells, 99% of the p75NTR+veCD71-ve and 33% of the p75NTR-veCD71+ve cells expressed both integrins, but just one week after culture, only 1.74% of the p75NTR+veCD71-ve cells still expressed p75NTR and only 0.32% still expressed CD71. Similar results were obtained when co-culturing p75NTR+ve and p75NTR-ve populations before analysis. Our results suggest that phenotype changes may be part of an intrinsic cellular mechanism to conserve levels of protein expression as they may found in the human body. In addition, in vitro culture may not offer ideal conditions for epithelial stem cell maintenance due to phenotype changes under standard culture conditions.

Phenotype changes of oral epithelial stem cells after in vitro culture

Abstract The aim of our study was to isolate populations of keratinocyte stem cells based on the expression of cell surface markers and to investigate whether the culture could affect their phenotype. keratinocytes from human oral mucosa were sorted based on the expression of the epithelial stem cell markers p75NTR and CD71. We also examined the co-expression of other epithelial stem markers such as integrins β1 and α6 and their stem cell-like proprieties in in vitro assays. Three passages after being sorted by MACS, more than 93% of the p75NTR+ve cells lost the expression of p75NTR, while 5.46% of the p75NTR-ve gained it. Within the small population of the p75NTR+ve cells, 88% co-expressed other epithelial stem cell markers such as integrins β1 and α6, while only 28% of p75NTR-ve cells co-expressed these markers. These results were confirmed by sorting cells by FACS. Additionally, when double staining was used for sorting cells, 99% of the p75NTR+veCD71-ve and 33% of the p75NTR-veCD71+ve cells expressed both integrins, but just one week after culture, only 1.74% of the p75NTR+veCD71-ve cells still expressed p75NTR and only 0.32% still expressed CD71. Similar results were obtained when co-culturing p75NTR+ve and p75NTR-ve populations before analysis. Our results suggest that phenotype changes may be part of an intrinsic cellular mechanism to conserve levels of protein expression as they may found in the human body. In addition, in vitro culture may not offer ideal conditions for epithelial stem cell maintenance due to phenotype changes under standard culture conditions.

Elucidation and Structural Modeling of CD71 as a Molecular Target for Cell-Specific Aptamer Binding.

Pancreatic cancer is a highly lethal malignancy associated with tissues of the pancreas. Early diagnosis and effective treatment are crucial to improving the survival rate of patients with pancreatic cancer. In a previous study, we employed the cell-SELEX strategy to obtain an ssDNA aptamer termed XQ-2d with high binding affinity for pancreatic cancer. Here, we first identify CD71 as the XQ-2d-binding target. We found that knockdown of CD71 abolished the binding of XQ-2d and that the binding affinity of XQ-2d is associated with membrane-bound CD71, rather than total CD71 levels. Competitive analysis revealed that XQ-2d shares the same binding site on CD71 with transferrin (Tf), but not anti-CD71 antibody. We then used a surface energy transfer (SET) nanoruler to measure the distance between the binding sites of XQ-2d and anti-CD71 antibody, and it was about 15 nm. Furthermore, we did molecular dynamics simulation to clarify that the spatial structure of XQ-2d and Tf competitively binding to CD71. We also engineered XQ-2d-mediated targeted therapy for pancreatic cancer, using an XQ-2d-based complex for loading doxorubicin (Dox). Because CD71 is overexpressed not only in pancreatic cancer but also in a variety of tumors, our work provides a systematic novel way of studying a potential biomarker and also promising tools for cancer diagnosis and therapy, opening new doors for effective cancer theranostics.

Downregulation of intrinsic apoptosis pathway in erythroblasts contributes to excessive erythrocytosis of chronic mountain sickness.

Chronic mountain sickness (CMS) has a higher incidence in the plateau region and is characterized by excessive erythrocytosis and hypoxemia. Bcl-2 family plays an important role in the process of erythropoiesis and the regulation of apoptosis. This study aimed to examine the change in apoptosis of erythroblasts in CMS patients and explore the involvement of Bcl-2 family. Bone marrow mononuclear cells (BMMNCs) were isolated by density gradient centrifugation from 18 CMS patients and 17 control participants. The apoptotic rate, mitochondrial membrane potential (MMP), the protein expression of caspase-3, TNFR, Fas, Bcl-2, Bax and Cyt-C were examined by flow cytometry, and mRNA expression was determined by real-time PCR. The results showed that apoptotic rate of erythroblasts was lower and MMP was higher in CMS group than in control group. The mRNA and protein expression levels of Bcl-2 were higher while Bax level was lower in CMS group than in control group. In CMS group, the apoptosis rate of CD71+ erythroblasts was negatively correlated with the ratio of CD71+ cells in BMMNCs and positively correlated with hemoglobin level. In conclusion, erythroblasts apoptosis is decreased due to the regulation of the expression of Bcl-2 family members in the erythroblasts of CMS patients.

Quantitative imaging of receptor-ligand engagement in intact live animals.

Maintaining an intact tumor environment is critical for quantitation of receptor-ligand engagement in a targeted drug development pipeline. However, measuring receptor-ligand engagement in vivo and non-invasively in preclinical settings is extremely challenging. We found that quantitation of intracellular receptor-ligand binding can be achieved using whole-body macroscopic lifetime-based Förster Resonance Energy Transfer (FRET) imaging in intact, live animals bearing tumor xenografts. We determined that FRET levels report on ligand binding to transferrin receptors conversely to raw fluorescence intensity. FRET levels in heterogeneous tumors correlate with intracellular ligand binding but strikingly, not with ubiquitously used ex vivo receptor expression assessment. Hence, MFLI-FRET provides a direct measurement of systemic delivery, target availability and intracellular drug delivery in preclinical studies. Here, we have used MFLI to measure FRET longitudinally in intact and live animals. MFLI-FRET is well-suited for guiding the development of targeted drug therapy in heterogeneous tumors in intact, live small animals.

Acute and Chronic Iron Overloading Differentially Modulates the Expression of Cellular Iron-homeostatic Molecules in Normal Rat Kidney.

Little is known about the renal responses to acute iron overloading. This study measured the renal tubular expression of transferrin receptor-1 (TfR1), cubilin/megalin receptors, hepcidin, ferroportin, and ferritin chains following subacute intoxication of 40 male Wistar rats with a single oral dose of ferrous iron (300 mg/kg). The animals were randomly subdivided into 4 equal subgroups at the time of necropsy (1, 2, 4, and 8 hr). The results were compared with the controls ( n=15) and with the chronic group ( n=15), which received iron for 4 weeks (75 mg/kg/day; 5 days/week). Although both toxicity models inhibited TfR1, they upregulated the cubilin/megalin receptors and hepcidin, and triggered iron deposition in tubular cells. The ferritin heavy-chain and ferroportin were downregulated in the 2-hr and 4-hr acute subgroups, whereas chronic toxicity promoted their expression, compared with controls. Moreover, the 4-hr and 8-hr subgroups had higher intracellular Fe+2 and marked cell apoptosis compared with the chronic group. In conclusion, the kidney appears to sustain iron reabsorption in both intoxication models. However, the cellular iron storage and exporter proteins were differentially expressed in both models, and their inhibition post-acute toxicity might contribute toward the intracellular accumulation of Fe+2, oxidative stress, and ferroptosis.

Prognostic Value of Transferrin Receptor-1 (CD71) Expression in Acute Lymphoblastic Leukemia.

BACKGROUND: Acute lymphoblastic leukemia (ALL) is the commonest childhood cancer. Transferrin receptor 1 (CD71) is a trans-membrane glycoprotein which has important role in iron homeostasis by acting as a gatekeeper regulating iron uptake from transferrin and is an attractive target for anti-cancer agents, particularly those that aim to induce lethal iron deprivation in malignant hematopoietic cells. AIM OF THE WORK: To assess the prognostic value of Transferrin receptor -1 (CD71) in children with newly diagnosed ALL. PATIENTS AND METHODS: This study was carried out on 75 patients with newly diagnosed ALL. Transferrin receptor-1 expression was analyzed on the bone marrow blasts by flow cytometry at time of diagnosis with positive CD71 expression is considered when ≥20% of malignant cells express this marker while negative expression is considered when <20% of malignant cells express this marker. RESULTS: Transferrin receptor-1 positive expression was detected in 45 patients (60%) while negative expression was found in the remaining 30 patients (40%). CD71 expression was significantly higher on T- ALL patients compared with B-ALL patients. Positive CD71 expression at diagnosis was significantly associated with bad clinical and laboratory prognostic factors as lymphadenopathy, higher white blood cell count, higher hemoglobin level, lower platelets count, and higher blast cells in peripheral blood and bone marrow and higher lactate dehydrogenase levels'. There were significant differences in disease free survival (DFS) and overall survival (OS) between positive and negative CD71 expression groups with significantly shorter DFS and OS in positive CD71 expression group compared to negative group. CONCLUSION AND RECOMMENDATIONS: 'Positive Transferrin receptor -1 (CD71) expression in patients with ALL is adverse prognostic factor and should be taken in consideration in designing future therapeutic strategies based on patient- specific risk factors'.

Aggregation-Induced Emission Probe for Specific Turn-On Quantification of Soluble Transferrin Receptor: An Important Disease Marker for Iron Deficiency Anemia and Kidney Diseases.

Transferrin receptor (TfR) is overexpressed on the surface of many cancer cells due to its vital roles in iron circulation and cellular respiration. Soluble transferrin receptor (sTfR), a truncated extracellular form of TfR in serum, is an important marker of iron deficiency anemia (IDA) and bone marrow failure in cancer patients. More recently, sTfR level in urine has been related to a specific kidney disease of Henoch-Schönlein purpura nephritis (HSPN). Despite the universal significance of sTfR, there is still a lack of a simple and sensitive method for the quantification of sTfR. Furthermore, it is desirable to have a probe that can detect both TfR and sTfR for further comparison study. In this work, we developed a water-soluble AIE-peptide conjugate with aggregation-induced emission (AIE) characteristics. Taking advantage of the negligible emission from molecularly dissolved tetraphenylethene (TPE), probe TPE-2T7 was used for the light-up detection of sTfR. The probe itself is nonemissive in aqueous solution, but it turns on its fluorescence upon interaction with sTfR to yield a detection limit of 0.27 µg/mL, which is much lower than the sTfR level in IDA patients. Furthermore, a proof-of-concept experiment validates the potential of the probe for diagnosis of HSPN by urine test.

[Siwu decoction improves iron deficiency anemia in infant rats and regulates iron metabolism].

To investigate the effect of Siwu decoction on improving iron deficiency anemia in infant rats and observe its regulatory effects on iron metabolism. SD rats were fed with low iron fodder for 2 weeks, and then the rats with hemoglobin level less than 75 g•L ⁻¹ were screened out and randomly divided into model group, Ferrous succinate 50 mg•kg ⁻¹ group, Siwu decoction 4 g•kg ⁻¹, 8 g•kg ⁻¹ and 16 g•kg ⁻¹ groups. After 4 weeks' gavage administration, Wright-Giemsa's staining of blood smear and HE staining of the livers were conducted, and all rats were tested for blood routine, serum iron, total iron binding capacity, serum ferritin, serum hepcidin and liver hepcidin. The expression levels of liver ferritin, transferrin and transferrin receptor 1 were also detected. The results showed that as compared with normal group, the activity level of model group was decreased, and the color and lustre of auricles and toes were pale white; the number of red blood cells was decreased; the volume was smaller, with an increased zone of central pallor; the body weight and blood routine parameters were decreased significantly; the livers were pale red, and the hepatic cords around thecentral veins were unclear and misaligned; the serum iron, serum ferritin, liver iron levels and the expression of liver ferritin were decreased significantly; the total iron binding capacity, serum hepcidin, liver hepcidin, the expression levels of liver transferrin and transferrin receptor 1 were significantly increased, indicating successful establishment of models. As compared with the model group, activity was increased in Siwu decoction group; the color and lustre of auricles and toes were ruddy; the number of red blood cells was increased; the volume was larger, with a decreased zone of central pallor; the body weight and blood routine parameters were increased significantly; the livers were red, hepatic cords around the central veins were clear and aligned;the serum iron, serum ferritin, liver iron levels and the expression of liver ferritin were significantly increased, the total iron binding capacity, serum hepcidin, liver hepcidin, the expression of liver transferrin and transferrin receptor 1 were decreased significantly. The results demonstrated that Siwu decoction had a certain effect on improving iron deficiency anemia in infant rats, and the mechanism may be associated with the regulatory effect of hepcidin iron metabolism.

[Mechanism for the inhibition of proliferation and promotion of apoptosis in Huh7.5 cells by iron overload].

Objective To investigate the effect of iron overload on biological activity and apoptosis in Huh7.5 cells. Methods Huh7.5 cells were cultured in the medium supplemented with 50, 100, 200 µmol/L ferric ammonium citrate (FAC). Fluorescence microscopy was employed to determine cell iron load labeled by Phen Green FL; proliferation activity of Huh7.5 cells was evaluated by MTT assay; protein and mRNA levels of transferrin receptor (TfR1), TfR2, divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1) in Huh7.5 cells were detected by Western blotting and real-time PCR, respectively; cell reactive oxygen species (ROS) labeled by dichlorofluorescin diacetate (DCFH-DA) and cell apoptosis labeled by annexinV-FITC/PI were analyzed by flow cytometry. Results FAC treatment increased intracellular iron load in a dose-dependent manner. Compared with control group, mRNA and protein expressions of TfR1, TfR2 and DMT1 were down-regulated, while mRNA and protein expression of FPN1 was significantly up-regulated in FAC treated groups. With the increasing dose of FAC, intracellular ROS level increased significantly and cell proliferation activity decreased significantly. The cell apoptosis rate in FAC treated groups were remarkably higher than that in control group, but after antioxidant N-acetylcysteine (NAC) was added, the cell apoptosis in FAC treated group was inhibited obviously. Conclusion Iron overload can inhibit the proliferation and promote the apoptosis of Huh7.5 cells through oxidative stress.

HPV16-E2 protein modifies self-renewal and differentiation rate in progenitor cells of human immortalized keratinocytes.

BACKGROUND: Cervical cancer is the fourth cause of death worldwide by cancer in women and is a disease associated to persistent infection with human papillomavirus (HPV), particularly from two high-risk types HPV16 and 18. The virus initiates its replicative cycle infecting cells located in the basal layer of the epithelium, where a small population of epithelial stem cells is located performing important functions of renewal and maintenance of the tissue. Viral E2 gene is one of the first expressed after infection and plays relevant roles in the replicative cycle of the virus, modifying fundamental processes in the infected cells. Thus, the aim of the present study was to demonstrate the presence of hierarchic subpopulations in HaCaT cell line and evaluate the effect of HPV16-E2 expression, on their biological processes. METHODS: HaCaT-HPV16-E2 cells were generated by transduction of HaCaT cell line with a lentiviral vector. The α6-integrin-CD71 expression profile was established by immunostaining and flow cytometric analysis. After sorting, cell subpopulations were analyzed in biological assays for self-renewal, clonogenicity and expression of stemness factors (RT-qPCR). RESULTS: We identified in HaCaT cell line three different subpopulations that correspond to early differentiated cells (α6-integrindim), transitory amplifying cells (α6-integrinbri/CD71bri) and progenitor cells (α6-integrinbri/CD71dim). The last subpopulation showed stem cell characteristics, such as self-renewal ability, clonogenicity and expression of the well-known stem cell factors SOX2, OCT4 and NANOG, suggesting they are stem-like cells. Interestingly, the expression of HPV16-E2 in HaCaT cells changed its α6-integrin-CD71 immunophenotype modifying the relative abundance of the cell subpopulations, reducing significantly the percentage of α6-integrinbri/CD71dim cells. Moreover, the expression of the stem cell markers was also modified, increasing the expression of SOX2 and NANOG, but decreasing notably the expression of OCT4. CONCLUSIONS: Our data demonstrated the presence of a small subpopulation with epithelial "progenitor cells" characteristics in the HaCaT cell line, and that HPV16-E2 expression on these cells induces early differentiation.

Expression of CD71 by flow cytometry in acute leukemias: More often seen in acute myeloid leukemia.

BACKGROUND: CD71 is a marker that has been usually used for identifying dysplasia in the erythroid series. We have tried to evaluate the expression of CD71 in various types of acute leukemias. MATERIALS AND METHODS: We studied 48 patients of acute leukemia, of which 25 were acute myeloid leukemia (AML), 13 were precursor B-acute lymphoblastic leukemia (B-ALL), 8 were T-ALL, and 2 were mixed phenotype acute leukemia (T/myeloid) as per the WHO classification. RESULTS: We found that the expression of CD71 was most prevalent in AMLs (84%), followed by T-ALL (50%) and least in B-ALL (30%). CONCLUSION: This finding clearly shows the higher expression of CD71 in AMLs compared to other common type of leukemias, such as B- and T-ALL. We suggest that the high expression of CD71 in AMLs could be used as a diagnostic marker and may also be used for minimal residual disease analysis after further studies in posttreatment scenario. This study is the first of its kind in the South Asian population.

Stress reticulocytes lose transferrin receptors by an extrinsic process involving spleen and macrophages.

As they mature into erythrocytes during normal erythropoiesis, reticulocytes lose surface transferrin receptors before or concurrently with reticulin. Exosome release accounts for most of the loss of transferrin receptors from reticulocytes. During erythropoietic stress, reticulocytes are released early from hematopoietic tissues and have increased reticulin staining and transferrin receptors. Flow cytometry of dually stained erythrocytes of mice recovering from phlebotomy demonstrated delayed loss of reticulin and transferrin receptors during in vitro maturation compared to in vivo maturation, indicating that an in vivo process extrinsic to the reticulocytes facilitates their maturation. Splenectomy or macrophage depletion by liposomal clodronate inhibited in vivo maturation of reticulocytes and increased the numbers of reticulin-negative, transferrin receptor-positive cells during and after recovery from phlebotomy. This reticulin-negative, transferrin receptor-positive population was rarely found in normal mice. Transmission electron microscopy demonstrated that the reticulin-negative, transferrin receptor-positive cells were elongated and discoid erythrocytes, but they had intracellular and surface structures that appeared to be partially degraded organelles. The results indicate that maturation of circulating stress reticulocytes is enhanced by an extrinsic process that occurs in the spleen and involves macrophage activity. Complete loss of reticulin with incomplete loss of surface transferrin receptors in this process produces a reticulin-negative, transferrin receptor-positive erythrocyte population that has potential utility for detecting prior erythropoietic stresses including bleeding, hemolysis and erythropoietin administration, even after recovery has been completed. Am. J. Hematol. 91:875-882, 2016. © 2016 Wiley Periodicals, Inc.

Real-Time Specific Light-Up Sensing of Transferrin Receptor: Image-Guided Photodynamic Ablation of Cancer Cells through Controlled Cytomembrane Disintegration.

Transferrin receptor (TfR) represents a unique target for specific imaging of cancer cells and targeted delivery of therapeutic reagents. Detection and qualification of TfR is thus of great importance for cancer diagnosis and therapy. In this contribution, a light-up probe TPETH-2T7 was developed by conjugating a red-emissive photosensitizer with aggregation-induced emission (AIE) characteristics to a TfR-targeting peptide T7. The probe is almost nonemissive by itself, but it gives turn-on fluorescence in the presence of TfR with a detection limit of 0.45 µg/mL. Cellular experiments show that the probe specifically binds to TfR-overexpressed cancer cells. Real-time imaging results reveal that the probe stains the MDA-MB-231 cell membrane in 30 min, which is followed by probe internalization. Experiments on image-guided photodynamic cancer ablation show that the therapeutic performance is better when TPETH-2T7 is localized on the cell membrane as compared to that being internalized into cells. Confocal laser scanning microscopy (CLSM) study reveals that cytomembrane disintegration allows quick ablation of MDA-MB-231 cells.

Scanning Electron Microscopy Reveals Two Distinct Classes of Erythroblastic Island Isolated from Adult Mammalian Bone Marrow.

Erythroblastic islands are multicellular clusters in which a central macrophage supports the development and maturation of red blood cell (erythroid) progenitors. These clusters play crucial roles in the pathogenesis observed in animal models of hematological disorders. The precise structure and function of erythroblastic islands is poorly understood. Here, we have combined scanning electron microscopy and immuno-gold labeling of surface proteins to develop a better understanding of the ultrastructure of these multicellular clusters. The erythroid-specific surface antigen Ter-119 and the transferrin receptor CD71 exhibited distinct patterns of protein sorting during erythroid cell maturation as detected by immuno-gold labeling. During electron microscopy analysis we observed two distinct classes of erythroblastic islands. The islands varied in size and morphology, and the number and type of erythroid cells interacting with the central macrophage. Assessment of femoral marrow isolated from a cavid rodent species (guinea pig, Cavis porcellus) and a marsupial carnivore species (fat-tailed dunnarts, Sminthopsis crassicaudata) showed that while the morphology of the central macrophage varied, two different types of erythroblastic islands were consistently identifiable. Our findings suggest that these two classes of erythroblastic islands are conserved in mammalian evolution and may play distinct roles in red blood cell production.