Heme-deficient primitive red blood cells induce HSPC ferroptosis by altering iron homeostasis during zebrafish embryogenesis

Fish vaccines promote blood cell transcriptional remodeling in Atlantic salmon against pathogens

Chilean salmon farming confronts persistent challenges, including climate change risks and pathogens, where the most prevalent diseases impacting Atlantic salmon are Caligidosis and Rickettsial Salmonid Septicemia (SRS). As a sustainable strategy, fish vaccines hold promise for preventing diseases and reducing the use of antibiotics. While most studies on Atlantic salmon responses to vaccines emphasize transcriptome profiling from tissues such as the liver, head kidney, and skin, blood cell transcriptomics to monitor immune response dynamics is emerging as a promising tool in salmon aquaculture. This study evaluated the Atlantic salmon blood cell transcriptome in response to vaccination and subsequent infection with the sea louse Caligus rogercresseyi and the intracellular bacterium Piscirickettsia salmonis. The vaccination trial included four groups: fish immunized with the recombinant IPath® vaccine and two commercial vaccines currently used in Chile for salmon production. (BlueGuard® and Alpha Ject LiVac® SRS), and the unvaccinated control group. The group vaccinated with IPath® showed a higher transcriptomic response than commercial vaccines. Additionally, all three groups significantly modulated genes associated with iron homeostasis and metabolism. Furthermore, the HIF-1 signaling pathway and ferroptosis were notably activated in the IPath® group, suggesting a potential role of IPath® in the hypoxia response and cell death. This research highlights the effectiveness of using Atlantic salmon blood cells to assess immune responses, offering valuable insights into the fish immune system without resorting to lethal sampling.

Deletion of hepcidin disrupts iron homeostasis and hematopoiesis in zebrafish embryogenesis

Iron is essential for cell growth and hematopoiesis, which is regulated by hepcidin (hamp). However, the role of hamp in zebrafish hematopoiesis remains unclear. Here, we have created a stable hamp knockout zebrafish model using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated nuclease 9 system (CRISPR/Cas9 system). Our study revealed that hamp deletion led to maternal iron overload in embryos, significantly downregulating hemoglobin genes and reducing hemoglobin content. Single-cell RNA sequencing identified abnormal expression patterns in blood progenitor cells, with a specific progenitor subtype showing increased ferroptosis and delayed development. By crossing hamp knockout zebrafish with a gata1+ line (blood cells labeled fish line), we confirmed ferroptosis in blood progenitor cells. These findings underscore the crucial role of hamp in iron regulation and hematopoiesis, offering novel insights into developmental biology and potential therapeutic targets for blood disorders.

RNA m5C methylation mediated by Ybx1 ensures hematopoietic stem and progenitor cell expansion

Hematopoietic stem and progenitor cells (HSPCs) undergo rapid transcriptional transitions among distinct cell states and functional properties during development, but the underlying molecular mechanism is largely unknown. Here, we characterize the mRNA m5C landscape of developing HSPCs in zebrafish and found that m5C modification is essential for HSPC expansion through maintaining mRNA stability. Deletion of the m5C reader, Y-box binding protein 1 (Ybx1), significantly inhibits the proliferation of HSPCs in zebrafish and mice. Mechanistically, Ybx1 recognizes m5C-modified mRNAs and maintains the stability of cell-cycle-related transcripts, thereby ensuring proper HSPC expansion. This study reveals the critical role of Ybx1-mediated mRNA m5C modification in developmental hematopoiesis and provides new insights and epitransciptomic strategies for optimizing HSPC expansion.

Catching the Big Fish in Big Data: A Meta-Analysis of Zebrafish Kidney scRNA-Seq Datasets Highlights Conserved Molecular Profiles of Macrophages and Neutrophils in Vertebrates

The innate immune system (IIS) is an ancient and essential defense mechanism that protects animals against a wide range of pathogens and diseases. Although extensively studied in mammals, our understanding of the IIS in other taxa remains limited. The zebrafish (Danio rerio) serves as a promising model organism for investigating IIS-related processes, yet the immunogenetics of fish are not fully elucidated. To address this gap, we conducted a meta-analysis of single-cell RNA sequencing (scRNA-seq) datasets from zebrafish kidney marrow, encompassing approximately 250,000 immune cells. Our analysis confirms the presence of key genetic pathways in zebrafish innate immune cells that are similar to those identified in mammals. Zebrafish macrophages specifically express genes encoding cathepsins, major histocompatibility complex class II proteins, integral membrane proteins, and the V-ATPase complex and demonstrate the enrichment of oxidative phosphorylation ferroptosis processes. Neutrophils are characterized by the significant expression of genes encoding actins, cytoskeleton organizing proteins, the Arp2/3 complex, and glycolysis enzymes and have demonstrated their involvement in GnRH and CLR signaling pathways, adherents, and tight junctions. Both macrophages and neutrophils highly express genes of NOD-like receptors, phagosomes, and lysosome pathways and genes involved in apoptosis. Our findings reinforce the idea about the existence of a wide spectrum of immune cell phenotypes in fish since we found only a small number of cells with clear pro- or anti-inflammatory signatures.

ALAS2 overexpression alleviates oxidative stress-induced ferroptosis in aortic aneurysms via GATA1 activation

Background

Aortic aneurysm, characterized by abnormal dilation of the aorta, poses significant health risks. This study aims to investigate the interaction between 5-aminolevulinate synthase 2 (ALAS2) and GATA-binding protein 1 (GATA1) in ferroptosis and oxidative stress responses in aortic aneurysm.

Methods

A weighted gene co-expression network analysis (WGCNA) was performed on the differentially expressed genes (DEGs) within the GSE9106 dataset to identify the key module. Subsequently, protein-protein interaction (PPI) network analysis was performed on the key module. Mouse aortic vascular smooth muscle cells (MOVAS) were treated with hydrogen peroxide (H2O2) to induce oxidative stress, and ferroptosis inducers and inhibitors were added to evaluate their effects on iron content and oxidative stress markers. Through a series of in vitro cellular experiments, we assessed cell viability, expression levels of GATA1 and iron mutation-associated proteins, as well as cellular phenotypes such as inflammatory responses and apoptosis rates.

Results

Three candidate genes (ALAS2, GYPA, and GYPB) were upregulated in the thoracic aortic aneurysm (TAA) samples of the GSE9106 dataset. The H2O2 treatment increased the MOVAS cells' iron content and oxidative stress, upregulated ALAS2 protein levels, and decreased the ferroptosis-related protein levels. ALAS2 overexpression reversed H2O2-induced apoptosis and increased the inflammatory cytokine levels. Additionally, the knockdown of GATA1 partially reversed the protective mechanism of overexpressed ALAS2 on H2O2-induced ferroptosis.

Conclusions

ALAS2 overexpression reduced H2O2-induced oxidative damage and iron-induced apoptosis in MOVAS cells, and GATA1 knockdown partially reversed this protective effect. These findings suggested that the ALAS2 and GATA1 regulatory pathways may be potential therapeutic targets in aortic aneurysms.

Environmental cadmium exposure perturbs systemic iron homeostasis via hemolysis and inflammation, leading to hepatic ferroptosis in common carp (Cyprinus carpio L.)

Cadmium (Cd) pollution is considered a pressing challenge to eco-environment and public health worldwide. Although it has been well-documented that Cd exhibits various adverse effects on aquatic animals, it is still largely unknown whether and how Cd at environmentally relevant concentrations affects iron metabolism. Here, we studied the effects of environmental Cd exposure (5 and 50 μg/L) on iron homeostasis and possible mechanisms in common carp. The data revealed that Cd elevated serum iron, transferrin saturation and iron deposition in livers and spleens, leading to the disruption of systemic iron homeostasis. Mechanistic investigations substantiated that Cd drove hemolysis by compromising the osmotic fragility and inducing defective morphology of erythrocytes. Cd concurrently exacerbated hepatic inflammatory responses, resulting in the activation of IL6-Stat3 signaling and subsequent hepcidin transcription. Notably, Cd elicited ferroptosis through increased iron burden and oxidative stress in livers. Taken together, our findings provide evidence and mechanistic insight that environmental Cd exposure could undermine iron homeostasis via erythrotoxicity and hepatotoxicity. Further investigation and ecological risk assessment of Cd and other pollutants on metabolism-related effects is warranted, especially under the realistic exposure scenarios.

The interactions between ineffective erythropoiesis and ferroptosis in β-thalassemia

In Guangxi, Hainan, and Fujian Province in southern China, β-thalassemia is a frequent monogenic hereditary disorder that is primarily defined by hemolytic anemia brought on by inefficient erythropoiesis. It has been found that ineffective erythropoiesis in β-thalassemia is closely associated with a high accumulation of Reactive oxygen species, a product of oxidative stress, in erythroid cells. During recent years, ferroptosis is an iron-dependent lipid peroxidation that involves abnormalities in lipid and iron metabolism as well as reactive oxygen species homeostasis. It is a recently identified kind of programmed cell death. β-thalassemia patients experience increased iron release from reticuloendothelial cells and intestinal absorption of iron, ultimately resulting in iron overload. Additionally, the secretion of Hepcidin is inhibited in these patients. What counts is both ineffective erythropoiesis and ferroptosis in β-thalassemia are intricately linked to the iron metabolism and Reactive oxygen species homeostasis. Consequently, to shed further light on the pathophysiology of β-thalassemia and propose fresh ideas for its therapy, this paper reviews ferroptosis, ineffective erythropoiesis, and the way they interact.