Different effects of granulocyte colony-stimulating factor and erythropoietin on erythropoiesis

Restraint Stress-Induced Neutrophil Inflammation Contributes to Concurrent Gastrointestinal Injury in Mice

Psychological stress increases risk of gastrointestinal tract diseases. However, the mechanism behind stress-induced gastrointestinal injury is not well understood. The objective of our study is to elucidate the putative mechanism of stress-induced gastrointestinal injury and develop an intervention strategy. To achieve this, we employed the restraint stress mouse model, a well-established method to study the pathophysiological changes associated with psychological stress in mice. By orally administering gut-nonabsorbable Evans blue dye and monitoring its plasma levels, we were able to track the progression of gastrointestinal injury in live mice. Additionally, flow cytometry was utilized to assess the viability, death, and inflammatory status of splenic leukocytes, providing insights into the stress-induced impact on the innate immune system associated with stress-induced gastrointestinal injury. Our findings reveal that neutrophils represent the primary innate immune leukocyte lineage responsible for stress-induced inflammation. Splenic neutrophils exhibited elevated expression levels of the pro-inflammatory cytokine IL-1, cellular reactive oxygen species, mitochondrial burden, and cell death following stress challenge compared to other innate immune cells such as macrophages, monocytes, and dendritic cells. Regulated cell death analysis indicated that NETosis is the predominant stress-induced cell death response among other analyzed regulated cell death pathways. NETosis culminates in the formation and release of neutrophil extracellular traps, which play a crucial role in modulating inflammation by binding to pathogens. Treatment with the NETosis inhibitor GSK484 rescued stress-induced neutrophil extracellular trap release and gastrointestinal injury, highlighting the involvement of neutrophil extracellular traps in stress-induced gastrointestinal inflammation. Our results suggest that neutrophil NETosis could serve as a promising drug target for managing psychological stress-induced gastrointestinal injuries.

Restraint Stress-Induced Immunosuppression Is Associated with Concurrent Macrophage Pyroptosis Cell Death in Mice

Psychological stress is widely acknowledged as a major contributor to immunosuppression, rendering individuals more susceptible to various diseases. The complex interplay between the nervous, endocrine, and immune systems underlies stress-induced immunosuppression. However, the underlying mechanisms of psychological-stress-induced immunosuppression remain unclear. In this study, we utilized a restraint stress mouse model known for its suitability in investigating physiological regulations during psychological stress. Comparing it with cold exposure, we observed markedly elevated levels of stress hormones corticosterone and cortisol in the plasma of mice subjected to restraint stress. Furthermore, restraint-stress-induced immunosuppression differed from the intravenous immunoglobulin-like immunosuppression observed in cold exposure, with restraint stress leading to increased macrophage cell death in the spleen. Suppression of pyroptosis through treatments of inflammasome inhibitors markedly ameliorated restraint-stress-induced spleen infiltration and pyroptosis cell death of macrophages in mice. These findings suggest that the macrophage pyroptosis associated with restraint stress may contribute to its immunosuppressive effects. These insights have implications for the development of treatments targeting stress-induced immunosuppression, emphasizing the need for further investigation into the underlying mechanisms.

The Effect of Low-Energy Laser-Driven Ultrashort Pulsed Electron Beam Irradiation on Erythropoiesis and Oxidative Stress in Rats

Anemia is a commonly observed consequence of whole-body exposure to a dose of X-ray or gamma irradiation of the order of the mean lethal dose in mammals, and it is an important factor for the determination of the survival of animals. The aim of this study was to unravel the effect of laser-driven ultrashort pulsed electron beam (UPEB) irradiation on the process of erythropoiesis and the redox state in the organism. Wistar rats were exposed to laser-driven UPEB irradiation, after which the level of oxidative stress and the activities of different antioxidant enzymes, as well as blood smears, bone marrow imprints and sections, erythroblastic islets, hemoglobin and hematocrit, hepatic iron, DNA, and erythropoietin levels, were assessed on the 1st, 3rd, 7th, 14th, and 28th days after irradiation. Despite the fact that laser-driven UPEB irradiation requires quite low doses and repetition rates to achieve the LD₅₀ in rats, our findings suggest that whole-body exposure with this new type of irradiation causes relatively mild anemia in rats, with subsequent fast recovery up to the 28th day. Moreover, this novel type of irradiation causes highly intense processes of oxidative stress, which, despite being relatively extinguished, did not reach the physiologically stable level even at the 28th day after irradiation due to the violations in the antioxidant system of the organism.

Emerging role of the itaconate-mediated rescue of cellular metabolic stress

Metabolic regulations play vital roles on maintaining the homeostasis of our body. Evidence have suggested that ATF3 and nuclear factor erythroid 2–related factor 2 (NRF2) are critical for maintaining cell function, metabolism, and inflammation/anti-inflammation regulations when cells are under stress, while the upstream regulators in the stressed cells remain elusive. Recent findings have shown that tricarboxylic acid cycle metabolites such as itaconate and succinate are not just mitochondrial metabolites, but rather important signaling mediators, involving in the regulations of metabolism, immune modulation. Itaconate exerts anti-inflammatory role through regulating ATF3 and NRF2 pathways under stressed conditions. In addition, itaconate inhibits succinate dehydrogenase, succinate oxidation and thus blocking succinate-mediated inflammatory processes. These findings suggest itaconate-ATF3 and itaconate-NRF2 axes are well-coordinated machineries that facilitate the rescue against cellular stress. Here, we review these fascinating discoveries, a research field may help the development of more effective therapeutic approach to manage stress-induced inflammation, tissue damage, and metabolic disorder.

Activating Transcription Factor 3 Protects against Restraint Stress-Induced Gastrointestinal Injury in Mice

Psychological stress increases the risk of gastrointestinal (GI) tract diseases, which involve bidirectional communication of the GI and nerves systems. Acute stress leads to GI ulcers; however, the mechanism of the native cellular protection pathway, which safeguards tissue integrality and maintains GI homeostasis, remains to be investigated. In a mouse model of this study, restraint stress induced GI leakage, abnormal tight junction protein expression, and cell death of gut epithelial cells. The expression of activating transcription factor 3 (ATF3), a stress-responsive transcription factor, is upregulated in the GI tissues of stressed animals. ATF3-deficient mice displayed an exacerbated phenotype of GI injuries. These results suggested that, in response to stress, ATF3 is part of the native cellular protective pathway in the GI system, which could be a molecular target for managing psychological stress-induced GI tract diseases.

New insight into the mechanism of granulocyte colony-stimulating factor (G-CSF) that induces the mobilization of neutrophils

Over the past 20 years, granulocyte colony-stimulating factor (G-CSF) has driven the attention of researchers as a therapeutic agent for curing patients suffering from neutropenia. Despite the successful use of G-CSF, it currently requires daily injections, which are inconvenient, expensive, and distressing for children. Therefore, an alternative strategy for using G-CSF for treatment is needed. Understanding the G-CSF structure, expression, mechanism of action, and how it induces neutrophils mobilization is crucial to producing promising cancer therapy. The ability of G-CSF to mobilize hematopoietic stem cells from the bone marrow into the blood circulation was consequently exploited and altered the practice of hematopoietic stem cell transplantation. This is the motivation for the current review, which sheds light on the history of G-CSF and then focuses on the mechanism of action upon binding to its receptor (G-CSFR) and how that had led to the stimulation of neutrophils mobilization. The findings of this review show new insight into the mechanism of G-CSF that induces neutrophils mobilization. Thus, Understanding the G-CSF will provide a more effective treatment for all neutropenia patients.

AQP0 is a novel surface marker for deciphering abnormal erythropoiesis

Background

Hematopoiesis occurs in the bone marrow, producing a complete spectrum of blood cells to maintain homeostasis. In addition to light microscopy, chromosome analysis, and polymerase chain reaction, flow cytometry is a feasible and fast method for quantitatively analyzing hematological diseases. However, because sufficient specific cell markers are scarce, dyserythropoietic diseases are challenging to identify through flow cytometry.

Methods

Bone marrow samples from C57BL/B6 mice and one healthy donor were analyzed using traditional two-marker (CD71 and glycophorin A) flow cytometry analysis. After cell sorting, the gene expressions of membrane proteins in early and late erythropoiesis precursors and in nonerythroid cells were characterized using microarray analysis.

Results

Among characterized gene candidates, aquaporin 0 (AQP0) expressed as a surface protein in early- and late-stage erythropoiesis precursors and was not expressed on nonerythroid cells. With the help of AQP0 staining, we could define up to five stages of erythropoiesis in both mouse and human bone marrow using flow cytometry. In addition, because patients with dyserythropoiesis generally exhibited a reduced population of APQ0^high cells relative to healthy participants, the analysis results also suggested that the levels of APQ0^high cells in early erythropoiesis serve as a novel biomarker that distinguishes normal from dysregulated erythropoiesis.

Conclusions

AQP0 was successfully demonstrated to be a marker of erythroid differentiation. The expression levels of AQP0 are downregulated in patients with dyserythropoiesis, indicating a critical role of AQP0 in erythropoiesis. Accordingly, the level of AQP0^high in early erythroid precursor cells may serve as a reference parameter for diagnosing diseases associated with dyserythropoiesis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02343-4.

An Overview of Different Strategies to Recreate the Physiological Environment in Experimental Erythropoiesis

Human erythropoiesis is a complex process leading to the production of mature, enucleated erythrocytes (RBCs). It occurs mainly at bone marrow (BM), where hematopoietic stem cells (HSCs) are engaged in the early erythroid differentiation to commit into erythroid progenitor cells (burst-forming unit erythroid (BFU-E) and colony-forming unit erythroid (CFU-E)). Then, during the terminal differentiation, several erythropoietin-induced signaling pathways trigger the differentiation of CFU-E on successive stages from pro-erythroblast to reticulocytes. The latter are released into the circulation, finalizing their maturation into functional RBCs. This process is finely regulated by the physiological environment including the erythroblast-macrophage interaction in the erythroblastic island (EBI). Several human diseases have been associated with ineffective erythropoiesis, either by a defective or an excessive production of RBCs, as well as an increase or a hemoglobinization defect. Fully understanding the production of mature red blood cells is crucial for the comprehension of erythroid pathologies as well as to the field of transfusion. Many experimental approaches have been carried out to achieve a complete differentiation in vitro to produce functional biconcave mature RBCs. However, the various protocols usually fail to achieve enough quantities of completely mature RBCs. In this review, we focus on the evolution of erythropoiesis studies over the years, taking special interest in efforts that were made to include the microenvironment and erythroblastic islands paradigm. These more physiological approaches will contribute to a deeper comprehension of erythropoiesis, improve the treatment of dyserythropoietic disorders, and break through the barriers in massive RBCs production for transfusion.

Efficacy of granulocyte colony stimulating factor in combination with erythropoiesis stimulating agents for treatment of anemia in patients with lower risk myelodysplastic syndromes: A systematic review

Anemic patients with lower risk myelodysplastic syndromes are frequently treated with erythropoiesis stimulating agents (ESA), eventually in combination with granulocyte colony stimulating factor (G-CSF). However, the evidence for the efficacy of a combined treatment remains controversial. The goal of our analysis was to assess the available evidence for a combined treatment. We performed a systematic review and identified only nine eligible studies. In two randomized controlled trials (n = 98), erythroid response rates were 33% and 40% after low-/standard-doses of ESA alone (10,000-30,000 rHuEPO equivalents/week) versus 65% and 73% after combination treatment. In seven trials with sequential drug administration (n = 393), erythroid response rates ranged from 12% to 71% after full-doses of ESA alone (60,000-80,000 rHuEPO equivalents/week) and from 35% to 74% after combination therapy. Our analysis supports an additional efficacy of G-CSF added to low-/standard-dose ESA, but the available data remains controversial, if G-CSF is added to full-dose ESA.