DNA binding to TLR9 expressed by red blood cells promotes innate immune activation and anemia

Cloning of Toll3 and Toll4 and association analysis among their SNP haplotypes and disease resistance in red swamp crayfish (Procambarus clarkii)

With the expansion of the culture scale of red swamp crayfish (Procambarus clarkii), the high incidence of diseases has seriously threatened the development of its industry. In this study, PcToll3 and PcToll4 were respectively cloned and explored SNPs among the germplasm populations, which had been identified relating to disease resistance in crayfish based on our previous study. A total of 3036 bp and 2820 bp of the open reading frame of PcToll3 and PcToll4 encoded 1011 and 939 amino acids, respectively. They were specially expressed in haemolymph, and significantly up-regulated expression after stimulation by Vibrio parahaemolyticus, Aeromonas hydrophila and white spot syndrome virus. It was found that the expression of downstream genes PcALF, PcCru, PcIMD, PcMyD88, and PcNF-κB were repressed after interference of PcToll3 and/or PcToll4. Totally, 16 and 19 SNPs in the coding region of PcToll3 and PcToll4 were mined, and the favoured haplotypes and the combinations of them were classified according to the associated SNPs with the disease resistance in crayfish. The haplotypes of Toll3-Hap1, Toll4-Hap1 and the combination of Toll3+Toll4-Hap1 were further validated that they had the stronger disease resistance comparing to others haplotypes, and the related KASP markers were developed for further breeding application. This study will advance our understanding of the function of the two Toll genes in crayfish, and provide the markers for the molecular breeding.

Erythroblastic island: the niche for erythroid terminal differentiation and beyond

The erythroblastic island (EBI) is a multicellular structure defined by the presence of 1 or 2 central macrophages surrounded by at least 3 erythroblasts. EBIs were initially proposed as a specialized microenvironment exclusively for erythroid terminal differentiation. Recent advancements in techniques such as lineage tracing mouse models, imaging flow cytometry, and single-cell RNA sequencing, accumulating evidence has provided novel insights that challenge this conventional view. Notably, the erythropoietin receptor has been identified as a novel marker for EBI macrophages. Additionally, neutrophils have been identified as novel cellular components of EBIs, raising the intriguing hypothesis that EBIs may support other hematopoietic lineage cells as well. Beyond the diverse cellular components of various hematopoietic lineages, even within the erythroid lineage, an immune-prone erythroblast subpopulation has been reported, although it remains unclear whether and how these immune-prone erythroblasts mature in EBIs. These observations indicate that EBIs are a heterogeneous population. In this review, we summarize the most recent findings on EBIs, discuss their potential immune functions, and provide a perspective for future investigations.

Microplastics/nanoplastics contribute to aging and age-related diseases: Mitochondrial dysfunction as a crucial role

The pervasive utilization of plastic products has led to a significant escalation in plastic waste accumulation. Concurrently, the implications of emerging pollutants such as microplastics (MPs) and nanoplastics (NPs) on human health are increasingly being acknowledged. Recent research has demonstrated that MPs/NPs may contribute to the onset of human aging and age-related diseases. Additionally, MPs/NPs have the potential to induce mitochondrial damage, resulting in mitochondrial dysfunction. Mitochondrial dysfunction is widely recognized as a hallmark of aging; thus, it is necessary to elucidate the relationship between them. In this article, we first elucidate the distribution of MPs/NPs in various environmental media, their pathways into the human body, and their subsequent distribution within human tissues and organs. Subsequently, we examine the interplay between MPs/NPs, mitochondrial dysfunction, and the aging process. We aspire that this article will enhance awareness regarding the toxicity of MPs/NPs while also offering a theoretical framework to support the development of improved regulatory policies in the future.

Mitochondrial DNA signals driving immune responses: Why, How, Where?

There has been a recent expansion in our understanding of DNA-sensing mechanisms. Mitochondrial dysfunction, oxidative and proteostatic stresses, instability and impaired disposal of nucleoids cause the release of mitochondrial DNA (mtDNA) from the mitochondria in several human diseases, as well as in cell culture and animal models. Mitochondrial DNA mislocalized to the cytosol and/or the extracellular compartments can trigger innate immune and inflammation responses by binding DNA-sensing receptors (DSRs). Here, we define the features that make mtDNA highly immunogenic and the mechanisms of its release from the mitochondria into the cytosol and the extracellular compartments. We describe the major DSRs that bind mtDNA such as cyclic guanosine-monophosphate-adenosine-monophosphate synthase (cGAS), Z-DNA-binding protein 1 (ZBP1), NOD-, LRR-, and PYD- domain-containing protein 3 receptor (NLRP3), absent in melanoma 2 (AIM2) and toll-like receptor 9 (TLR9), and their downstream signaling cascades. We summarize the key findings, novelties, and gaps of mislocalized mtDNA as a driving signal of immune responses in vascular, metabolic, kidney, lung, and neurodegenerative diseases, as well as viral and bacterial infections. Finally, we define common strategies to induce or inhibit mtDNA release and propose challenges to advance the field.

Red blood cells undergo lytic programmed cell death involving NLRP3

The canonical complement-mediated lysis of mature red blood cells (RBCs) leads to severe pathogenesis. However, inhibition strategies targeting complement are not always as efficient as expected, indicating that unknown mechanisms are awaiting elucidation. In this study, we investigate the intracellular events in mature RBCs following complement activation. The collected evidence demonstrates that complement-induced hemolysis is a caspase-8-dependent programmed RBC death. Furthermore, short NLRP3 (miniNLRP3) fragments in RBCs are identified to engage in the assembly of NLRP3-apoptosis-associated speck-like protein containing a CARD (ASC)-caspase-8 complex. Activated caspase-8 directly induces the proteolysis of β-spectrin, thereby disrupting the skeletal network of the RBC membrane, a process we refer to as spectosis. Spectosis signaling is also activated in autoimmune hemolytic anemia or paroxysmal nocturnal hemoglobinuria, and the inhibition of spectosis significantly reduced complement-induced hemolysis. These findings reveal a programmed death cascade in mature RBCs, which may have important implications for the treatment of hemolytic disorders.

Serial 'deep-sampling' PCR of fragmented DNA reveals the wide range of Trypanosoma cruzi burden among chronically infected human, macaque, and canine hosts, and allows accurate monitoring of parasite load following treatment

Infection with the protozoan parasite Trypanosoma cruzi is generally well-controlled by host immune responses, but appears to be rarely eliminated. The resulting persistent, low-level infection results in cumulative tissue damage with the greatest impact generally in the heart in the form of chagasic cardiomyopathy. The relative success in immune control of T. cruzi infection usually averts acute phase death but has the negative consequence that the low-level presence of T. cruzi in hosts is challenging to detect unequivocally. Thus, it is difficult to identify those who are actively infected and, as well, problematic to gauge the impact of treatment, particularly in the evaluation of the relative efficacy of new drugs. In this study, we employ DNA fragmentation and high numbers of replicate PCR reaction ('deep-sampling') and to extend the quantitative range of detecting T. cruzi in blood by at least three orders of magnitude relative to current protocols. When combined with sampling blood at multiple time points, deep sampling of fragmented DNA allowed for detection of T. cruzi in all infected hosts in multiple host species, including humans, macaques, and dogs. In addition, we provide evidence for a number of characteristics not previously rigorously quantified in the population of hosts with naturally acquired T. cruzi infection, including, a >6 log variation between chronically infected individuals in the stable parasite levels, a continuing decline in parasite load during the second and third years of infection in some hosts, and the potential for parasite load to change dramatically when health conditions change. Although requiring strict adherence to contamination-prevention protocols and significant resources, deep-sampling PCR provides an important new tool for assessing therapies and for addressing long-standing questions in T. cruzi infection and Chagas disease.

Archaea-inspired deoxyribonuclease I liposomes prevent multiple organ dysfunction in sepsis

Neutrophil extracellular traps (NETs) and circulating cell-free DNA (cfDNA) are pivotal in driving excessive inflammation and organ damage during sepsis, with their levels correlating positively with sepsis severity in both patients and murine models. Despite the ability of deoxyribonuclease I (DNase I) to degrade NETs and cfDNA, its short half-life and rapid degradation limit its therapeutic effectiveness. To address this challenge, we developed a methyl-branched liposome fused with a red blood cell membrane for the systemic delivery of DNase I (DNase I/Rm-Lipo). The efficacy of DNase I/Rm-Lipo was evaluated in the stimulated immune cells and septic model. The data confirmed that DNase I/Rm-Lipo efficiently removed excess NETs and cfDNA in activated neutrophils. Following injection, DNase I/Rm-Lipo exhibited an extended circulation time, effectively suppressing neutrophil activation and regulating macrophage polarization to mitigate inflammation and prevent organ dysfunction in septic mice. These findings highlight the therapeutic potential of DNase I/Rm-Lipo as a promising candidate for sepsis management by targeting the degradation of NETs and cfDNA.

Mitochondrial DNA released by senescent tumor cells enhances PMN-MDSC-driven immunosuppression through the cGAS-STING pathway

Mitochondrial dysfunction is a hallmark of cellular senescence. Here, we investigated whether senescent cells release mitochondrial (mt)DNA into the extracellular space and its impact on innate immunity. We found that both primary senescent cells and tumor cells undergoing therapy-induced senescence actively released mtDNA into the extracellular environment. mtDNA released by senescent cells was packaged within extracellular vesicles and selectively transferred to polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) in the tumor microenvironment. Upon uptake, extracellular mtDNA enhanced the immunosuppressive activity of PMN-MDSCs via cGAS-STING-NF-κB signaling, thereby promoting tumor progression. While STING activation directly induced NF-κB signaling, it also activated PKR-like endoplasmic reticulum kinase (PERK), which further amplified NF-κB activity, in PMN-MDSCs. mtDNA release from senescent cells was mediated by voltage-dependent anion channels (VDACs), and pharmacological inhibition of VDAC reduced extracellular mtDNA levels, reversed PMN-MDSC-driven immunosuppression, and enhanced chemotherapy efficacy in prostate cancer mouse models. These findings suggest that targeting mtDNA release could reprogram the immunosuppressive tumor microenvironment, improving therapeutic outcomes for chemotherapy-treated patients.

Mechanical adaptivity of red blood cell flickering to extrinsic membrane stiffening by the solid-like biosurfactant β-Aescin

β-Aescin is a natural additive employed for treatments of vascular insufficiency, hence its impact in red blood cell (RBC) adaptivity has been conjectured. Here, we report a study about the mechanical impact of the membrane stiffener aescin on the flickering motions of live RBCs maintained at the homeostatic status. An active flickering, or nonequilibrium fluctuation dynamics has been revealed by mapping flickering motions in single RBCs treated or not with aescin. Experiments show that active RBC flickers adapt mechanically to β-escin, unlike the passive thermal fluctuations observed in lipid bilayers without an active skeleton. Mechanical connections for active flickering are theoretically argued to exist between an effective viscoelastic softness bestowed by the spectrin membrane cytoskeleton and the observed stiffness imposed by aescin as a rigidity modulator. From the unveiled diffusive mechanics, we model an adaptive RBC homeostasis that recapitulates the active flickering phenomenon as an optimal membrane softness upon a regulated friction as observed under aescin-induced membrane hardening. From a physiological perspective, RBC flicker adaptiveness to rigidization is discussed according to regulatory principles of energy conservation and minimal dissipation.

Cytosolic nucleic acid sensing as driver of critical illness: mechanisms and advances in therapy

Nucleic acids from both self- and non-self-sources act as vital danger signals that trigger immune responses. Critical illnesses such as acute respiratory distress syndrome, sepsis, trauma and ischemia lead to the aberrant cytosolic accumulation and massive release of nucleic acids that are detected by antiviral innate immune receptors in the endosome or cytosol. Activation of receptors for deoxyribonucleic acids and ribonucleic acids triggers inflammation, a major contributor to morbidity and mortality in critically ill patients. In the past decade, there has been growing recognition of the therapeutic potential of targeting nucleic acid sensing in critical care. This review summarizes current knowledge of nucleic acid sensing in acute respiratory distress syndrome, sepsis, trauma and ischemia. Given the extensive research on nucleic acid sensing in common pathological conditions like cancer, autoimmune disorders, metabolic disorders and aging, we provide a comprehensive summary of nucleic acid sensing beyond critical illness to offer insights that may inform its role in critical conditions. Additionally, we discuss potential therapeutic strategies that specifically target nucleic acid sensing. By examining nucleic acid sources, sensor activation and function, as well as the impact of regulating these pathways across various acute diseases, we highlight the driving role of nucleic acid sensing in critical illness.

Erythroid progenitor cell-mediated spleen-tumor interaction deteriorates cancer immunity

Understanding both local and systemic immunity is essential to optimizing the effectiveness of immunotherapy. However, the dynamic alterations in systemic immunity during tumor development are yet to be clearly defined. Here, we identified a previously unrecognized connection that bridges the interaction between the spleen and tumor through erythroid progenitor cells (EPCs), which suppress tumor immunity and promote tumor progression. We performed the single-cell RNA-seq and RNA-seq to demonstrate the presence of EPCs and identify the characteristic and an immunomodulatory role of EPCs during tumor progression. These tumor-hijacked EPCs proliferate in situ in spleens and impaired systemic and local antitumor response through the interaction between tumor and spleen. Specifically, the splenic CD45- EPCs secreted heparin-binding growth factor to regulate PD-L1-mediated immunosuppression of splenic CD45+ EPCs. Educated CD45+ EPCs from the spleen then migrated to the tumors via the CCL5/CCR5 axis, thereby weakening local antitumor immunity. Consequently, targeting EPCs not only revitalized antitumor immunity but also improved the anti-PD-L1 effect by promoting intratumoral T cell infiltration. Importantly, CD45+ EPCs are associated with immunosuppression and reduced survival in patients with head and neck squamous cell carcinoma. Collectively, these findings reveal the role of EPCs in orchestrating the interaction between the spleen and tumor, which could have significant implications for the development of more effective cancer immunotherapy.

Insights from omics research on plant-based diets and cardiometabolic health

Plant-based diets emphasize higher intake of plant foods and are low in animal products. Individuals following plant-based diets have a lower risk of chronic conditions; however, the mechanisms underlying these associations are not completely understood. Omics data have opened opportunities to investigate the mechanistic effect of dietary intake on health outcomes. Here, we review omics analyses of plant-based diets in feeding and observational studies, showing that although metabolomics and proteomics identified candidate biomarkers and distinct pathways modifiable by plant-based diets, current evidence from transcriptomics and methylomics is limited. We also argue that future studies should examine how unhealthful plant-based diets are associated with a higher risk of health outcomes and integrate multiple omics data from feeding studies to provide further mechanistic insights.

Emerging concepts in the molecular cell biology and functions of mammalian erythrocytes

Erythrocytes, or red blood cells, are essential components of vertebrate blood, comprising approximately 45% of human blood volume. Their distinctive features, including small size, biconcave shape, extended lifespan (∼115 days), and lack of a nucleus or other membrane-bound organelles, make them unique among mammalian cell types. Traditionally regarded as passive carriers of oxygen and carbon dioxide, erythrocytes were long thought to function merely as hemoglobin-filled sacs, incapable of gene expression or roles beyond gas transport. However, advancements in molecular biology have revealed a more complex picture. Recent studies have identified various RNA types within erythrocytes, demonstrated globin mRNA translation, and uncovered miRNA-mediated defenses against Plasmodium infection. Beyond gas exchange, erythrocytes play critical roles in regulating regional blood flow via nitric oxide, contribute to innate immunity through toll-like receptors, transport amino acids between tissues, and maintain water homeostasis. Furthermore, emerging technologies have repurposed erythrocytes as drug-delivery vehicles, opening new avenues for therapeutic applications. This review highlights these recent discoveries and explores the expanding functional landscape of erythrocytes, shedding light on their multifaceted roles in physiology and medicine.

The effect of GM-CSF and predictors of treatment outcome in pediatric septic shock patients

BACKGROUND

Pediatric septic shock is a critical condition associated with high mortality rates, largely due to sepsis-induced immunosuppression. Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been explored as a therapeutic intervention to counteract this immunosuppression. Despite its potential, the efficacy of GM-CSF in pediatric septic shock has not been clearly established. This study aims to investigate the impact of GM-CSF administration on survival rates and to identify key predictors of treatment outcomes in pediatric septic shock patients.

METHODS

We conducted a retrospective cohort study at the Pediatric Intensive Care Unit (PICU) of Children's Hospital of Fudan University, Shanghai, from January 1, 2019, to December 31, 2023. The study included pediatric patients diagnosed with septic shock, analyzing their demographic data, GM-CSF and adjunctive therapies, laboratory results, and clinical outcomes. We employed univariate and multivariate logistic regression models to assess the influence of GM-CSF on 28-day mortality and identify significant predictors of treatment outcomes.

RESULTS

The study included 200 pediatric patients, with 66 receiving GM-CSF treatment and 134 not treated with GM-CSF. The initial comparison showed a higher 28-day mortality in the GM-CSF group (59.1%) compared to the non-GM-CSF group (35.1%, P = 0.001). Notably, after adjustment for confounding factors, multivariate analysis revealed that the effect of GM-CSF treatment on 28-day mortality among pediatric septic shock patients did not reach statistical significance, with an odds ratio (OR) of 0.472 and a 95% confidence interval (CI) ranging from 0.153 to 1.457 (P = 0.192). However, the analysis indicated a potential trend suggesting that GM-CSF treatment may contribute to a reduction in 28-day mortality. In addition, significant predictors of treatment outcomes included hematopoietic stem cell transplantation (HSCT), lactic acid (LAC) levels, hospital-acquired septic shock (HASS), red blood cell (RBC) count, and platelet (PLT) count.

CONCLUSIONS

GM-CSF treatment may benefit pediatric septic shock patients, especially those with higher lactic acid, and lower RBC and platelet counts. These factors, which are significant predictors of outcomes, should be monitored during therapy.

Mitophagy in relation to chronic inflammation/ROS in aging

Various assaults on mitochondria occur during the human aging process, contributing to mitochondrial dysfunction. This mitochondrial dysfunction is intricately connected with aging and diseases associated with it. In vivo, the accumulation of defective mitochondria can precipitate inflammatory and oxidative stress, thereby accelerating aging. Mitophagy, an essential selective autophagy process, plays a crucial role in managing mitochondrial quality control and homeostasis. It is a highly specialized mechanism that systematically removes damaged or impaired mitochondria from cells, ensuring their optimal functioning and survival. By engaging in mitophagy, cells are able to maintain a balanced and stable environment, free from the potentially harmful effects of dysfunctional mitochondria. An ever-growing body of research highlights the significance of mitophagy in both aging and age-related diseases. Nonetheless, the association between mitophagy and inflammation or oxidative stress induced by mitochondrial dysfunction remains ambiguous. We review the fundamental mechanisms of mitophagy in this paper, delve into its relationship with age-related stress, and propose suggestions for future research directions.

Chronic benzene exposure impairs the self-renewal capacity of HSPCs in C57BL/6 mice

In this study, we aimed to investigate the effects of chronic benzene exposure on the self-renewal capacity of C57BL/6 bone marrow HSPCs. Twenty-four male C57BL/6 mice were randomly divided into two groups: the control group and the benzene-exposed group. Mice in the benzene-exposed group inhaled 1,000 mg/m3 (308 ppm; conversion factor: 20 °C, 101 kPa, 1 ppm = 3.25 mg/m3) benzene for 32 weeks and the control group mice inhaled clean air. The peripheral blood hematological alterations were monitored every two weeks. Competitive bone marrow transplantation was performed to assess the self-renewal capacity of bone marrow HSPCs and the donor cell chimerism was quantified through flow cytometry. By the fourth week of benzene exposure, significant reductions in leukocytes, erythrocytes, and hemoglobin levels (P < 0.05) were observed, suggesting the development of benzene poisoning in mice. In the B6.SJL recipient mice, the chimerism ratio of bone marrow cells from C57BL/6 donors exposed to benzene for 20 weeks significantly decreased after transplantation (16 weeks post-transplant: 52.58% ± 17.38% in controls vs. 3.89% ± 1.96% in the benzene group, P < 0.05). Furthermore, the chimerism ratio in recipients of 32-week benzene-exposed donors approached zero by week 84 post-transplant, suggesting a loss of self-renewal capacity in bone marrow HSPCs due to benzene exposure. The study concludes that bone marrow suppression and the diminished self-renewal ability of C57BL/6 bone marrow HSPCs may lead to bone marrow failure in mice, contributing to the potential occurrence of MDS.

Probiotic DNA regulates intestinal Th2 polarization by inducing epithelial cells to produce PD-L1

Th2 polarization is a characteristic feature of many immune diseases; its pathogenesis is still being elucidated. Probiotics have immune regulatory effects. This study is aimed at testing the impact of Lactobacillus rhamnosus (LR) DNA on regulating Th2 polarization and elucidating its underlying mechanism. In this study, ovalbumin plus alum protocol was used to establish the Th2 polarization status in the mouse intestine. Mice received LR-DNA gavage daily for five days. The expression of programmed cell death ligand-1 (PD-L1) in intestinal epithelial cells was assessed using RT-qPCR, enzyme-linked immunosorbent assay, and immunohistochemistry. The results showed that the expression of PD-L1 was detected in mouse intestinal epithelial cells, which was up regulated by LR-DNA gavage daily for 5 days. The expression of PD-L1 was also detected in T84 cells, which could be increased by exposing them to LR-DNA in culture. RNA sequencing results showed that the gene activities of Kdm5a, foxo1 and Pdl1 could be upregulated by LR-DNA in mouse intestinal epithelial cells. The epithelial cell-derived PD-L1 induced the activated Th2 cell apoptosis by interacting with programmed cell death protein-1 (PD-1). Administration of LR-DNA, but not live probiotics, alleviated experimental Th2 polarization in a food allergy mouse model. In conclusion, LR-DNA induces intestinal epithelial cells to produce PD-L1, which induces the activated Th2 cell apoptosis. Administration of LR-DNA mitigated experimental Th2 polarization in the intestine.

Human erythrocytes' perplexing behaviour: erythrocytic microRNAs

Erythrocytes have the potential role in erythropoiesis and disease diagnosis. Thought to have lacked nucleic acid content, mammalian erythrocytes are nevertheless able to function for 120-140 days, metabolize heme, maintain oxidative stress, and so on. Mysteriously, erythrocytes proved as largest repositories of microRNAs (miRNAs) some of which are selectively retained and function in mature erythrocytes. They have unique expression patterns and have been found to be linked to specific conditions such as sickle cell anaemia, high-altitude hypoxia, chronic mountain sickness, cardiovascular and metabolic conditions as well as host-parasite interactions. They also have been implicated in cell storage-related damage and the regulation of its survival. However, the mechanism by which miRNAs function in the cell remains unclear. Investigations into the molecular mechanism of miRNAs in erythrocytes via extracellular vesicles have provided important clues in research studies on Plasmodium infection. Erythrocytes are also the primary source of circulating miRNAs but, how they affect the plasma/serum miRNAs profiles are still poorly understood. Erythrocyte-derived exosomal miRNAs, can interact with various body cell types, and have easy access to all regions, making them potentially crucial in various pathophysiological conditions. Which can also improve our understanding to identify potential treatment options and discovery related to non-invasive diagnostic markers. This article emphasizes the importance of erythrocytic miRNAs while focusing on the enigmatic behaviour of erythrocytes. It also sheds light on how this knowledge may be applied in the future to enhance the state of erythrocyte translational research from the standpoint of erythrocytic miRNAs.

Short term high-fat diet induced liver ILC1 differentiation associated with the TLR9 activation

The health impact of dietary fat is a significant nutritional concern. However, the effects of high-fat diet on immune system particularly the liver regional immune function remains still unclear. Liver ILC1 has been recently identified as playing crucial roles in anti-viral defense, liver regeneration, and protection against acute liver injury. Here, in a mouse model, we uncovered that short term high-fat diet for 2 weeks obviously increased the frequency and number of ILC1 in liver. The production of TNF-α and expressions of TRAIL, CXCR3 and CXCR6 were also increased. Furthermore, EASY-RNAseq and ATAC-seq of liver ILC1 clarified the transcriptome characteristics and chromatin accessibility in response to short term high-fat diet, which were involved with lymphocyte differentiation. Mechanistically, we demonstrated that accumulation of liver ILC1 induced by short term high-fat diet was dependent on a TLR9-mediated differentiation through TLR9 inhibitor. Taken together, these findings shed light on the effect and underlying mechanism of short term high-fat diet on liver ILC1 differentiation and provide nutritional strategies and theoretical basis for the liver regional immune function regulation.

Mitochondrial dysfunction in the pathogenesis of acute pancreatitis

The mechanism of cell damage during acute pancreatitis (AP) has not been fully elucidated, and there is still a lack of specific or effective treatments. Increasing evidence has implicated mitochondrial dysfunction as a key event in the pathophysiology of AP. Mitochondrial dysfunction is closely related to calcium (Ca2+) overload, intracellular adenosine triphosphate depletion, mitochondrial permeability transition pore openings, loss of mitochondrial membrane potential, mitophagy damage and inflammatory responses. Mitochondrial dysfunction is an early triggering event in the initiation and development of AP, and this organelle damage may precede the release of inflammatory cytokines, intracellular trypsin activation and vacuole formation of pancreatic acinar cells. This review provides further insight into the role of mitochondria in both physiological and pathophysiological aspects of AP, aiming to improve our understanding of the underlying mechanism which may lead to the development of therapeutic and preventive strategies for AP.

Potential Correlation Between Hematological Parameters and Palpitation in Outpatients With COVID-19: A Retrospective Study

BACKGROUND

Research on heart injury caused by COVID-19 is limited to large observational and retrospective cohort studies using imaging or pathological data. Reported changes in the levels of myocardial markers in severe diseases have been limited, with few studies on mild infections. The effects of COVID-19 on cardiac function and changes in myocardial marker levels have not yet been reported.

METHODS

We analyzed data from outpatient blood samples collected at Beijing Anzhen Hospital during the 2022 COVID-19 outbreak and used the same periods in 2020 and 2021 as controls, focusing on changes in routine blood tests, coagulation, myocardial markers, and other blood indices in patients with palpitations.

RESULTS

The number of patients with palpitations increased by 4.87-fold during the COVID-19 mass outbreak in 2022. The indices of myocardial damage did not show any symptom-related increases but decreased within the normal range. The proportion of patients with palpitations whose D-dimer and fibrinogen/fibrin degradation product (FDP) values exceeded the reference ranges increased, as did the numbers of neutrophils, monocytes, and platelets. In this retrospective analysis, we found little change in the myocardial markers in patients with mild COVID-19.

CONCLUSIONS

In patients with mild COVID-19, attention should be diverted from detecting myocardial markers to changes in coagulation test results, focusing on the levels of coagulation indices to improve circulation and prevent thrombosis.

Thiostrepton: multifaceted biological activities and its applications in treatment of inflammatory diseases

Thiostrepton (TST) is a naturally occurring oligopeptide antibiotic with a demonstrated capacity to antagonize a broad spectrum of Gram-positive bacteria. It has been utilized as a safe antimicrobial agent in veterinary medicine. Despite its therapeutic potential, the clinical application of TST has been constrained by its poor solubility and bioavailability. However, an increasing number of studies indicate that TST possesses diverse pharmacological activities, including its significant role in microbe resistance and cancer countering. Notably, recent studies have pointed out that TST also possesses anti-inflammatory potential. It has exhibited promising therapeutic efficacy across various in vivo and in vitro disease models, including non-alcoholic fatty liver disease, inflammatory bowel disease, sepsis, psoriasis-like inflammation, and periodontitis. In this review, we describe the various pharmacological activities of TST, particularly its anti-inflammatory activity demonstrated in a variety of inflammatory diseases and the underlying mechanisms. These effects highlight the potential of TST as an anti-inflammatory agent for the treatment of inflammation diseases and for enhancing cellular therapies.

Red blood cells capture and deliver bacterial DNA to drive host responses during polymicrobial sepsis

Red blood cells (RBCs), traditionally recognized for their role in transporting oxygen, play a pivotal role in the body's immune response by expressing TLR9 and scavenging excess host cell-free DNA. DNA capture by RBCs leads to accelerated RBC clearance and triggers inflammation. Whether RBCs can also acquire microbial DNA during infections is unknown. Murine RBCs acquire microbial DNA in vitro, and bacterial DNA-induced (bDNA-induced) macrophage activation was augmented by WT, but not Tlr9-deleted, RBCs. In a mouse model of polymicrobial sepsis, RBC-bound bDNA was elevated in WT mice but not in erythroid Tlr9-deleted mice. Plasma cytokine analysis in these mice revealed distinct sepsis clusters characterized by persistent hypothermia and hyperinflammation in the most severely affected mice. RBC Tlr9 deletion attenuated plasma and tissue IL-6 production in the most severely affected group. Parallel findings in humans confirmed that RBCs from patients with sepsis harbored more bDNA than did RBCs from healthy individuals. Further analysis through 16S sequencing of RBC-bound DNA illustrated distinct microbial communities, with RBC-bound DNA composition correlating with plasma IL-6 in patients with sepsis. Collectively, these findings unveil RBCs as overlooked reservoirs and couriers of microbial DNA, capable of influencing host inflammatory responses in sepsis.

Erythronecroptosis: an overview of necroptosis or programmed necrosis in red blood cells

Necroptosis is considered a programmed necrosis that requires receptor-interacting protein kinase 1 (RIPK1), receptor-interacting protein kinase 3 (RIPK3), and pore-forming mixed lineage kinase domain-like protein (MLKL) to trigger a regulated cell membrane lysis. Membrane rupture in necroptosis has been shown to fuel innate immune response due to release of damage-associated molecular patterns (DAMPs). Recently published studies indicate that mature erythrocytes can undergo necroptosis as well. In this review, we provide an outline of multiple cell death modes occurring in erythrocytes, discuss possible immunological aspects of diverse erythrocyte cell deaths, summarize available evidence related to the ability of erythrocytes to undergo necroptosis, outline key involved molecular mechanisms, and discuss the potential implication of erythrocyte necroptosis in the physiology and pathophysiology. Furthermore, we aim to highlight the interplay between necroptosis and eryptosis signaling in erythrocytes, emphasizing specific characteristics of these pathways distinct from their counterparts in nucleated cells. Thus, our review provides a comprehensive summary of the current knowledge of necroptosis in erythrocytes. To reflect critical differences between necroptosis of nucleated cells and necroptosis of erythrocytes, we suggest a term erythronecroptosis for necroptosis of enucleated cells.

Targeting erythroid progenitor cells for cancer immunotherapy

Immunotherapy, especially immune checkpoint blockade therapy, represents a major milestone in the history of cancer therapy. However, the current response rate to immunotherapy among cancer patients must be improved; thus, new strategies for sensitizing patients to immunotherapy are urgently needed. Erythroid progenitor cells (EPCs), a population of immature erythroid cells, exert potent immunosuppressive functions. As a newly recognized immunosuppressive population, EPCs have not yet been effectively targeted. In this review, we summarize the immunoregulatory mechanisms of EPCs, especially for CD45+ EPCs. Moreover, in view of the regulatory effects of EPCs on the tumor microenvironment, we propose the concept of EPC-immunity, present existing strategies for targeting EPCs, and discuss the challenges encountered in both basic research and clinical applications. In particular, the impact of existing cancer treatments on EPCs is discussed, laying the foundation for combination therapies. The aim of this review is to provide new avenues for improving the efficacy of cancer immunotherapy by targeting EPCs.

Serial 'deep-sampling' PCR of fragmented DNA reveals the wide range of Trypanosoma cruzi burden among chronically infected hosts and allows accurate monitoring of parasite load following treatment

Infection with the protozoan parasite Trypanosoma cruzi is generally well-controlled by host immune responses, but appears to be rarely eliminated. The resulting persistent, low-level infection results in cumulative tissue damage with the greatest impact generally in the heart in the form of chagasic cardiomyopathy. The relative success in immune control of T. cruzi infection usually averts acute phase death but has the negative consequence that the low-level presence of T. cruzi in hosts is challenging to detect unequivocally. Thus, it is difficult to identify those who are actively infected and, as well, problematic to gauge the impact of treatment, particularly in the evaluation of the relative efficacy of new drugs. In this study we employ DNA fragmentation and high numbers of replicate PCR reaction ('deep-sampling') to extend the quantitative range of detecting T. cruzi in blood by at least 3 orders of magnitude relative to current protocols. When combined with sampling blood at multiple time points, deep sampling of fragmented DNA allowed for detection of T. cruzi in all infected hosts in multiple host species. In addition, we provide evidence for a number of characteristics not previously rigorously quantified in the population of hosts with naturally acquired T. cruzi infection, including, a > 6-log variation between chronically infected individuals in the stable parasite levels, a continuing decline in parasite load during the second and third years of infection in some hosts, and the potential for parasite load to change dramatically when health conditions change. Although requiring strict adherence to contamination-prevention protocols and significant resources, deep-sampling PCR provides an important new tool for assessing new therapies and for addressing long-standing questions in T. cruzi infection and Chagas disease.

The emerging role of mtDNA release in sepsis: Current evidence and potential therapeutic targets

Sepsis is a systemic inflammatory reaction caused by infection, and severe sepsis can develop into septic shock, eventually leading to multiorgan dysfunction and even death. In recent years, studies have shown that mitochondrial damage is closely related to the occurrence and development of sepsis. Recent years have seen a surge in concern over mitochondrial DNA (mtDNA), as anomalies in this material can lead to cellular dysfunction, disruption of aerobic respiration, and even death of the cell. In this review, we discuss the latest findings on the mechanisms of mitochondrial damage and the molecular mechanisms controlling mitochondrial mtDNA release. We also explored the connection between mtDNA misplacement and inflammatory activation. Additionally, we propose potential therapeutic targets of mtDNA for sepsis treatment.

Erythroid progenitor cell modulates cancer immunity: Insights and implications

The emergence of immunotherapies such as immune checkpoint blockade (ICB) has markedly enhanced cancer treatment outcomes for numerous patients. Nevertheless, the effectiveness of immunotherapy demonstrates substantial variation across different cancer types and individual patients. The immunosuppressive characteristics of the tumor microenvironment (TME) play a crucial role in contributing to this variation. Typically, people focus on cells with immunosuppressive functions in the TME, such as tumor-associated macrophages (TAMs), but research on TAMs alone cannot fully explain the complex structure and composition of the TME. Recent studies have reported that tumors can induce erythroid progenitor cells (EPCs) to exert immunosuppressive functions, not only acting within the TME but also secreting artemin in the spleen to promote tumor progression. In this review, we summarize the recent research on EPCs and tumors in recent years. We elucidate the mechanisms by which EPCs exert immunosuppressive functions in tumor-bearing conditions. In this review, we further propose potential therapeutic strategies targeting EPCs and emphasize the importance of in-depth exploration of the mechanisms by which EPCs regulate tumors and the immune system, as well as the significant clinical value of developing corresponding drugs.

Probiotic nucleotides increase IL-10 expression in airway macrophages to mitigate airway allergy

BACKGROUND

Dysfunctional immune regulation plays a crucial role in the pathogenesis of airway allergies. Macrophages are one of the components of the immune regulation cells. The aim of this study is to elucidate the role of lysine demethylase 5 A (KDM5A) in maintaining macrophages' immune regulatory ability.

METHODS

DNA was extracted from Lactobacillus rhamnosus GG to be designated as LgDNA. LgDNA was administered to the mice through nasal instillations. M2 macrophages (M2 cells) were isolated from the airway tissues using flow cytometry.

RESULTS

We found that airway M2 cells of mice with airway Th2 polarization had reduced amounts of IL-10 and KDM5A. Mice with Kdm5a deficiency in M2 cells showed the airway Th2 polarization. The expression of Kdm5a in airway M2 cells was enhanced by nasal instillations containing LgDNA. KDM5A mediated the effects of LgDNA on inducing the Il10 expression in airway M2 cells. Administration of LgDNA mitigated experimental airway allergy.

CONCLUSIONS

M2 macrophages in the airway tissues of mice with airway allergy show low levels of KDM5A. By upregulating KDM5A expression, LgDNA can increase Il10 expression and reconcile airway Th2 polarization.

Elevated mtDNA content in RBCs promotes oxidative stress may be responsible for faster senescence in men

BACKGROUND

Both we and others have found that RBC counts are significantly lower in older compared to younger. However, when gender is factored in, a significant age-related decrease of RBC counts is observed only in men but not in women.

METHODS

qPCR and confocal microscopy were used to detect the presence of mtDNA in RBCs. Flow cytometry and specific inhibitors were used to determine how RBCs uptake cf-mtDNA. The peripheral blood was collected from 202 young adults and 207 older adults and RBC and plasma were isolated. The levels of TLR9+RBCs and apoptotic RBCs after uptake of cf-mtDNA by RBCs were measured by flow cytometry. The kit detects changes in SOD and MDA levels after cf-mtDNA uptake by RBCs. Young RBCs (YR) and old RBCs (OR) from single individuals were separated by Percoll centrifugation.

RESULTS

We found a significant decrease in RBC counts and a significant increase in the RDW with aging only in men. We also found that significantly elevated mtDNA content in RBCs was observed only in men during aging and was not found in women. Further studies demonstrated that RBCs could take up cf-mtDNA via TLR9, and the uptake of mtDNA might lead to a decrease in the RBC number and an increase in RDW due to an increase of oxidative stress.

CONCLUSIONS

The RBC mtDNA content might be a potential marker of RBC aging and the elevated RBC mtDNA content might be the cause of faster senescence in males than females.

Chimeric Antigen-LgDNA Nanoparticles Attenuate Airway Th2 Polarization

Introduction

The therapeutic efficacy for airway allergies needs to be improved. Th2 polarization is a primary pathological feature of airway allergies. We constructed chimeric antigen-LgDNA (Lactobacillus rhamnosus DNA) nanoparticles (CAP-NPs). The effects of CAP-NPs on reconciling airway Th2 polarization were tested.

Methods

In this study, disulfide bond-linked antigen-major histocompatibility complex II (MHC II)-LgDNA nanoparticles (NPs) were constructed and designated CAP-NPs. An airway Th2 polarization mouse model was established to test the effects of CAP-NPs on suppressing the Th2 response.

Results

The CAP-NP components of ovalbumin (OVA), major histocompatibility complex II (MHC II), and LgDNA were confirmed in a series of laboratory tests. The CAP-NPs remained stable at pH7.2 for at least 96 h. In in vitro experiments, CAP-NPs bound to the surface of OVA-specific CD4+ T cells, which resulted in apoptosis of the antigen-specific CD4+ T cells. Removal of any of the three components from the NPs abolished the induction of apoptosis of antigen specific CD4+ T cells. CAP-NPs increased the expression of lysine-specific demethylase 5A (KDM5A) in CD4+ T cells. Histone H3K9 and the gene promoter of caspase 8 were demethylated by KDM5A, which led to transcription and expression of the caspase 8 gene. Administration of CAP-NPs significantly alleviated experimental airway Th2 polarization through activating the caspase 8-apoptosis signaling pathway.

Discussion

In this paper, we constructed CAP-NPs that could induce antigen-specific CD4+ T cell apoptosis. Administration of CAP-NPs efficiently alleviated experimental airway Th2 polarization.

Disease tolerance as immune defense strategy in bats: One size fits all?

Bats are natural reservoirs for zoonotic pathogens, yet the determinants of microbial persistence as well as the specific functionality of their immune system remain largely enigmatic. Their propensity to harbor viruses lethal to humans and/or livestock, mostly in absence of clinical disease, makes bats stand out among mammals. Defending against pathogens relies on avoidance, resistance, and/or tolerance strategies. In bats, disease tolerance has recently gained increasing attention as a prevailing host defense paradigm. We here summarize the current knowledge on immune responses in bats in the context of infection with zoonotic agents and discuss concepts related to disease tolerance. Acknowledging the wide diversity of bats, the broad spectrum of bat-associated microbial species, and immune-related knowledge gaps, we identify research priorities necessary to provide evidence-based proofs for disease tolerance in bats. Since disease tolerance relies on networks of biological processes, we emphasize that investigations beyond the immune system, using novel technologies and computational biology, could jointly advance our knowledge about mechanisms conferring bats reservoir abilities. Although disease tolerance may not be the "one fit all" defense strategy, deciphering disease tolerance in bats could translate into novel therapies and inform prevention of spillover infections to humans and livestock.

The heterogeneity of erythroid cells: insight at the single-cell transcriptome level

Erythroid cells, the most prevalent cell type in blood, are one of the earliest products and permeate through the entire process of hematopoietic development in the human body, the oxygen-transporting function of which is crucial for maintaining overall health and life support. Previous investigations into erythrocyte differentiation and development have primarily focused on population-level analyses, lacking the single-cell perspective essential for comprehending the intricate pathways of erythroid maturation, differentiation, and the encompassing cellular heterogeneity. The continuous optimization of single-cell transcriptome sequencing technology, or single-cell RNA sequencing (scRNA-seq), provides a powerful tool for life sciences research, which has a particular superiority in the identification of unprecedented cell subgroups, the analyzing of cellular heterogeneity, and the transcriptomic characteristics of individual cells. Over the past decade, remarkable strides have been taken in the realm of single-cell RNA sequencing technology, profoundly enhancing our understanding of erythroid cells. In this review, we systematically summarize the recent developments in single-cell transcriptome sequencing technology and emphasize their substantial impact on the study of erythroid cells, highlighting their contributions, including the exploration of functional heterogeneity within erythroid populations, the identification of novel erythrocyte subgroups, the tracking of different erythroid lineages, and the unveiling of mechanisms governing erythroid fate decisions. These findings not only invigorate erythroid cell research but also offer new perspectives on the management of diseases related to erythroid cells.

mtDNA amplifies beryllium sulfate-induced inflammatory responses via the cGAS-STING pathway in 16HBE cells

Beryllium sulfate (BeSO4) can cause inflammation through the mechanism, which has not been elucidated. Mitochondrial DNA (mtDNA) is a key contributor of inflammation. With mitochondrial damage, released mtDNA can bind to specific receptors (e.g., cGAS) and then activate related pathway to promote inflammatory responses. To investigate the mechanism of mtDNA in BeSO4-induced inflammatory response in 16HBE cells, we established the BeSO4-induced 16HBE cell inflammation model and the ethidium bromide (EB)-induced ρ016HBE cell model to detect the mtDNA content, oxidative stress-related markers, mitochondrial membrane potential, the expression of the cGAS-STING pathway, and inflammation-related factors. Our results showed that BeSO4 caused oxidative stress, decline of mitochondrial membrane potential, and the release of mtDNA into the cytoplasm of 16HBE cells. In addition, BeSO4 induced inflammation in 16HBE cells by activating the cGAS-STING pathway. Furthermore, mtDNA deletion inhibited the expression of cGAS-STING pathway, IL-10, TNF-α, and IFN-β. This study revealed a novel mechanism of BeSO4-induced inflammation in 16HBE cells, which contributes to the understanding of the molecular mechanism of beryllium and its compounds-induced toxicity.

Innate immune sensing of cell death in disease and therapeutics

Innate immunity, cell death and inflammation underpin many aspects of health and disease. Upon sensing pathogens, pathogen-associated molecular patterns or damage-associated molecular patterns, the innate immune system activates lytic, inflammatory cell death, such as pyroptosis and PANoptosis. These genetically defined, regulated cell death pathways not only contribute to the host defence against infectious disease, but also promote pathological manifestations leading to cancer and inflammatory diseases. Our understanding of the underlying mechanisms has grown rapidly in recent years. However, how dying cells, cell corpses and their liberated cytokines, chemokines and inflammatory signalling molecules are further sensed by innate immune cells, and their contribution to further amplify inflammation, trigger antigen presentation and activate adaptive immunity, is less clear. Here, we discuss how pattern-recognition and PANoptosome sensors in innate immune cells recognize and respond to cell-death signatures. We also highlight molecular targets of the innate immune response for potential therapeutic development.

Whole exome sequencing identifies genetic markers of enterovirus susceptibility in East Asians

Introduction

Following acute enterovirus (EV) infection, outcomes vary based on factors like the immune response, viral cell entry receptor expression levels, tissue tropism, and genetic factors of both the host and virus. While most individuals exhibit mild, self-limited symptoms, others may suffer severe complications or prolonged infections that can lead to autoimmune disorders.

Methods

To elucidate host responses to EV infection, we performed whole exome sequencing on blood samples from both infected and uninfected individuals. Our initial focus was on genes encoding EV entry receptors-PSGL-1, SCARB2, and ANAXA2 for EV-A71, and CD155 for poliovirus-and on host genes ACBD3 and PI4KΒ, crucial for EV replication.

Results

Although no specific genetic variants directly associated with EV infection were identified, we discovered 118 variants across 116 genes enriched in East Asian populations through multi-layered variant filtering. These variants were further analyzed for their potential impacts on organs, biological processes, and molecular pathways. Phenome-wide association studies were conducted to refine our understanding of their contributions to EV infection susceptibility.

Discussion

Our findings aim to develop a predictive panel based on these 118 variants, which could help susceptible individuals during EV outbreaks, guiding targeted clinical interventions and preventative strategies.

Mitochondrial regulation of erythropoiesis in homeostasis and disease

Erythroid cells undergo a highly complex maturation process, resulting in dynamic changes that generate red blood cells (RBCs) highly rich in haemoglobin. The end stages of the erythroid cell maturation process primarily include chromatin condensation and nuclear polarization, followed by nuclear expulsion called enucleation and clearance of mitochondria and other organelles to finally generate mature RBCs. While healthy RBCs are devoid of mitochondria, recent evidence suggests that mitochondria are actively implicated in the processes of erythroid cell maturation, erythroblast enucleation and RBC production. However, the extent of mitochondrial participation that occurs during these ultimate steps is not completely understood. This is specifically important since abnormal RBC retention of mitochondria or mitochondrial DNA contributes to the pathophysiology of sickle cell and other disorders. Here we review some of the key findings so far that elucidate the importance of this process in various aspects of erythroid maturation and RBC production under homeostasis and disease conditions.

Identification and validation of ferroptosis related markers in erythrocyte differentiation of umbilical cord blood-derived CD34+ cell by bioinformatic analysis

Ferroptosis has been observed to play an important role during erythrocyte differentiation (ED). However, the biological gene markers and ferroptosis mechanisms in ED remain unknown. We downloaded the datasets of ED in human umbilical cord blood-derived CD34+ cells from the Gene Expression Omnibus database. Using median differentiation time, the sample was categorized into long and short groups. The differentially expressed ferroptosis-related genes (DE-FRGs) were screened using differential expression analysis. The enrichment analyses and a protein-protein interaction (PPI) network were conducted. To predict the ED stage, a logistic regression model was constructed using the least absolute shrinkage and selection operator (LASSO). Overall, 22 DE-FRGs were identified. Ferroptosis-related pathways were enriched using Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes. Gene Set Enrichment Analysis and Gene Set Variation Analysis revealed the primary involvement of DE-FRGs in JAK-STAT, MAPK, PI3K-AKT-mTORC1, WNT, and NOTCH signaling pathways. Ten-hub DE-FRGs were obtained using PPI analysis. Furthermore, we constructed mRNA-microRNA (miRNA) and mRNA-transcription factor networks. Immune cell infiltration levels differed significantly during ED. LASSO regression analysis established a signature using six DE-FRGs (ATF3, CDH2, CHAC1, DDR2, DPP4, and GDF15) related to the ED stage. Bioinformatic analyses identified ferroptosis-associated genes during ED, which were further validated. Overall, we identified ferroptosis-related genes to predict their correlations in ED. Exploring the underlying mechanisms of ferroptosis may help us better understand pathophysiological changes in ED and provide new evidence for clinical transformation.

Macrophage polarization and its impact on idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a lung disease that worsens over time, causing fibrosis in the lungs and ultimately resulting in respiratory failure and a high risk of death. Macrophages play a crucial role in the immune system, showing flexibility by transforming into either pro-inflammatory (M1) or anti-inflammatory (M2) macrophages when exposed to different stimuli, ultimately impacting the development of IPF. Recent research has indicated that the polarization of macrophages is crucial in the onset and progression of IPF. M1 macrophages secrete inflammatory cytokines and agents causing early lung damage and fibrosis, while M2 macrophages support tissue healing and fibrosis by releasing anti-inflammatory cytokines. Developing novel treatments for IPF relies on a thorough comprehension of the processes involved in macrophage polarization in IPF. The review outlines the regulation of macrophage polarization and its impact on the development of IPF, with the goal of investigating the possible therapeutic benefits of macrophage polarization in the advancement of IPF.

Human red blood cells express the RNA sensor TLR7

Red blood cells (RBCs) express the nucleic acid-binding toll-like receptor 9 (TLR9) and bind CpG-containing DNA. However, whether human RBCs express other nucleic acid-binding TLRs is unknown. Here we show that human RBCs express the RNA sensor TLR7. TLR7 is present on the red cell membrane and is associated with the RBC membrane protein Band 3. In patients with SARS-CoV2-associated sepsis, TLR7-Band 3 interactions in the RBC membrane are increased when compared with healthy controls. In vitro, RBCs bind synthetic ssRNA and RNA from ssRNA viruses. Thus, RBCs may serve as a previously unrecognized sink for exogenous RNA, expanding the repertoire of non-gas exchanging functions performed by RBCs.

Erythroid-intrinsic activation of TLR8 impairs erythropoiesis in inherited anemia

Inherited non-hemolytic anemia is a group of rare bone marrow disorders characterized by erythroid defects. Although concerted efforts have been made to explore the underlying pathogenetic mechanisms of these diseases, the understanding of the causative mutations are still incomplete. Here we identify in a diseased pedigree that a gain-of-function mutation in toll-like receptor 8 (TLR8) is implicated in inherited non-hemolytic anemia. TLR8 is expressed in erythroid lineage and erythropoiesis is impaired by TLR8 activation whereas enhanced by TLR8 inhibition from erythroid progenitor stage. Mechanistically, TLR8 activation blocks annexin A2 (ANXA2)-mediated plasma membrane localization of STAT5 and disrupts EPO signaling in HuDEP2 cells. TLR8 inhibition improves erythropoiesis in RPS19+/- HuDEP2 cells and CD34+ cells from healthy donors and inherited non-hemolytic anemic patients. Collectively, we identify a gene implicated in inherited anemia and a previously undescribed role for TLR8 in erythropoiesis, which could potentially be explored for therapeutic benefit in inherited anemia.

Red blood cell flickering activity locally controlled by holographic optical tweezers

Red blood cells possess a singular mechanobiology, enabling efficient navigation through capillaries smaller than their own size. Their plasma membrane exhibits non-equilibrium shape fluctuation, often reported as enhanced flickering activity. Such active membrane motion is propelled by motor proteins that mediate interactions between the spectrin skeleton and the lipid bilayer. However, modulating the flickering in living red blood cells without permanently altering their mechanical properties represents a significant challenge. In this study, we developed holographic optical tweezers to generate a force field distributed along the equatorial membrane contour of individual red blood cells. In free-standing red blood cells, we observed heterogeneous flickering activity, attributed to localized membrane kickers. By employing holographic optical forces, these active kickers can be selectively halted under minimal invasion. Our findings shed light on the dynamics of membrane flickering and established a manipulation tool that could open new avenues for investigating mechanotransduction processes in living cells.

Erythrocytes of the common carp are immune sentinels that sense pathogen molecular patterns, engulf particles and secrete pro-inflammatory cytokines against bacterial infection

Introduction

Red blood cells (RBCs), also known as erythrocytes, are underestimated in their role in the immune system. In mammals, erythrocytes undergo maturation that involves the loss of nuclei, resulting in limited transcription and protein synthesis capabilities. However, the nucleated nature of non-mammalian RBCs is challenging this conventional understanding of RBCs. Notably, in bony fishes, research indicates that RBCs are not only susceptible to pathogen attacks but express immune receptors and effector molecules. However, given the abundance of RBCs and their interaction with every physiological system, we postulate that they act in surveillance as sentinels, rapid responders, and messengers.

Methods

We performed a series of in vitro experiments with Cyprinus carpio RBCs exposed to Aeromonas hydrophila, as well as in vivo laboratory infections using different concentrations of bacteria.

Results

qPCR revealed that RBCs express genes of several inflammatory cytokines. Using cyprinid-specific antibodies, we confirmed that RBCs secreted tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ). In contrast to these indirect immune mechanisms, we observed that RBCs produce reactive oxygen species and, through transmission electron and confocal microscopy, that RBCs can engulf particles. Finally, RBCs expressed and upregulated several putative toll-like receptors, including tlr4 and tlr9, in response to A. hydrophila infection in vivo.

Discussion

Overall, the RBC repertoire of pattern recognition receptors, their secretion of effector molecules, and their swift response make them immune sentinels capable of rapidly detecting and signaling the presence of foreign pathogens. By studying the interaction between a bacterium and erythrocytes, we provide novel insights into how the latter may contribute to overall innate and adaptive immune responses of teleost fishes.

Hemocompatibility studies in nanotoxicology: Hemolysis or eryptosis? (A review)

Hemocompatibility evaluation is an important step in nanotoxicological studies. It is generally accepted that nanomaterials promote lysis of erythrocytes, blood clotting, alter phagocytosis, and upregulate pro-inflammatory cytokines. However, there are no standardized guidelines for testing nanomaterials hemocompatibility despite the fact that nanomaterials enter the bloodstream and interact with blood cells. In this review, the current knowledge on the ability of nanomaterials to induce distinct cell death modalities of erythrocytes is highlighted primarily focusing on hemolysis and eryptosis. This review aims to summarize the molecular mechanisms underlying erythrotoxicity of nanomaterials and critically compare the sensitivity and efficiency of hemolysis or eryptosis assays for nanomaterials blood compatibility testing. The list of eryptosis-inducing nanomaterials is growing, but it is still difficult to generalize how physico-chemical properties of nanoparticles affect eryptosis degree and molecular mechanisms involved. Thus, another aim of this review is to raise the awareness of eryptosis as a nanotoxicological tool to encourage the corresponding studies. It is worthwhile to consider adding eryptosis to in vitro nanomaterials hemocompatibility testing protocols and guidelines.

Marine Polysaccharides Carrageenans Enhance Eryptosis and Alter Lipid Order of Cell Membranes in Erythrocytes

Aim In the current study, hemocompatibility of three major commercially available types of carrageenans (ι, κ and λ) was investigated focusing on eryptosis.

MATERIALS AND METHODS

Carrageenans of ι-, κ- and λ-types were incubated with washed erythrocytes (hematocrit 0.4%) at 0-1-5-10 g/L for either 24 h or 48 h. Incubation was followed by flow cytometry-based quantitative analysis of eryptosis parameters, including cell volume, cell membrane scrambling and reactive oxygen species (ROS) production, lipid peroxidation markers and confocal microscopy-based evaluation of intracellular Ca2+ levels, assessment of lipid order in cell membranes and the glutathione antioxidant system. Confocal microscopy was used to assess carrageenan cellular internalization using rhodamine B isothiocyanate-conjugated carrageenans.

RESULTS

All three types of carrageenans were found to trigger eryptosis. Pro-eryptotic properties were type-dependent and λ-carrageenan had the strongest impact inducing phosphatidylserine membrane asymmetry, changes in cell volume, Ca2+ signaling and oxidative stress characterized by ROS overproduction, activation of lipid peroxidation and severe glutathione system depletion. Eryptosis induction by carrageenans does not require their uptake by erythrocytes. Changes in physicochemical properties of cell membrane were also type-dependent. No carrageenan-induced generation of superoxide and hydroxyl radicals was observed in cell-free milieu.

CONCLUSIONS

Our findings suggest that ι-, κ- and λ-types trigger eryptosis in a type-dependent manner and indicate that carrageenans can be further investigated as potential eryptosis-regulating therapeutic agents.

Amino acid supplementation confers protection to red blood cells before Plasmodium falciparum bystander stress

ABSTRACT

Malaria is a highly oxidative parasitic disease in which anemia is the most common clinical symptom. A major contributor to the malarial anemia pathogenesis is the destruction of bystander, uninfected red blood cells (RBCs). Metabolic fluctuations are known to occur in the plasma of individuals with acute malaria, emphasizing the role of metabolic changes in disease progression and severity. Here, we report conditioned medium from Plasmodium falciparum culture induces oxidative stress in uninfected, catalase-depleted RBCs. As cell-permeable precursors to glutathione, we demonstrate the benefit of pre-exposure to exogenous glutamine, cysteine, and glycine amino acids for RBCs. Importantly, this pretreatment intrinsically prepares RBCs to mitigate oxidative stress.

Mitochondrial DNA release and sensing in innate immune responses

Mitochondria are pleiotropic organelles central to an array of cellular pathways including metabolism, signal transduction, and programmed cell death. Mitochondria are also key drivers of mammalian immune responses, functioning as scaffolds for innate immune signaling, governing metabolic switches required for immune cell activation, and releasing agonists that promote inflammation. Mitochondrial DNA (mtDNA) is a potent immunostimulatory agonist, triggering pro-inflammatory and type I interferon responses in a host of mammalian cell types. Here we review recent advances in how mtDNA is detected by nucleic acid sensors of the innate immune system upon release into the cytoplasm and extracellular space. We also discuss how the interplay between mtDNA release and sensing impacts cellular innate immune endpoints relevant to health and disease.

Red blood cells function as reservoirs of tumor DNA

Novel screening techniques for early detection of lung cancer are urgently needed. Profiling circulating tumor cell-free DNA (ctDNA) has emerged as a promising tool for biopsy-free tumor genotyping. However, both the scarcity and short half-life of ctDNA substantially limit the sensitivity and clinical utility of ctDNA detection methodologies. Our discovery that red blood cells (RBCs) sequester mitochondrial DNA opens a new avenue for detecting circulating nucleic acids, as RBCs represent an unrecognized reservoir of circulating nucleic acid. Here, we show that RBCs acquire tumor DNA following coculture with lung cancer cell lines harboring Kirsten rat sarcoma viral oncogene homolog (KRAS) and epidermal growth factor receptor (EGFR) mutations. RBC-bound tumor DNA is detectable in patients with early-stage non-small cell lung cancer (NSCLC) but not in healthy controls by qPCR. Our results collectively uncover a previously unrecognized yet easily accessible reservoir of tumor DNA, offering a promising foundation for future RBC-based tumor diagnostics.NEW & NOTEWORTHY We present a novel method for lung cancer detection by revealing RBCs as a reservoir for tumor DNA, overcoming the limitations of current circulating tumor ctDNA methodologies. By demonstrating that RBCs can capture tumor DNA, including critical mutations found in lung cancer, we provide a promising, biopsy-free avenue for early cancer diagnostics. This discovery opens up exciting possibilities for developing RBC-based diagnostic tools, significantly enhancing the sensitivity and clinical utility of noninvasive cancer detection.