Inflammation and ER stress downregulate BDH2 expression and dysregulate intracellular iron in macrophages

Cytotoxicity and Antibiofilm Activity of Silver-Polypropylene Nanocomposites

The development of biocompatible nanomaterials that interface with human skin and tissue is critical for advancing prosthetics and other therapeutic medical needs. In this perspective, the development of nanoparticles with cytotoxicity and antibiofilm properties and biocompatibility characteristics are important. Metallic silver (Ag) exhibits good biocompatibility, but it is often challenging to integrate it into a nanocomposite without compromising its antibiofilm properties for optimal applications. In this study, new polymer nanocomposites (PNCs) with ultra-low filling content (0.0023-0.046 wt%) of Ag nanoplates were manufactured and tested. The cytotoxicity and antibiofilm activity of different composites with polypropylene (PP) matrix were examined. At first, PNCs surface were analyzed by means of AFM (atomic force microscopy) with phase contrast evaluation and FTIR (Fourier-transform infrared spectroscopy) to study the Ag nanoplates distribution. Subsequently, the cytotoxicity and growth properties of biofilms were assessed by MTT assay protocol and detection of nitric oxide radicals. Antibacterial and antibiofilm activities were measured against Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (K. pneumoniae). The PNCs with silver exhibited antibiofilm activity although they did not inhibit regular planktonic bacterial growth. Moreover, the PNCs were not cytotoxic to mammalian cells and did not induce significant immune response. These features reveal the potential of the PNCs developed in this study for usage in fabrication of prosthetics and other smart structures for biomedical applications.

Vascular calcification: Molecular mechanisms and therapeutic interventions

Vascular calcification (VC) is recognized as a pathological vascular disorder associated with various diseases, such as atherosclerosis, hypertension, aortic valve stenosis, coronary artery disease, diabetes mellitus, as well as chronic kidney disease. Therefore, it is a life-threatening state for human health. There were several studies targeting mechanisms of VC that revealed the importance of vascular smooth muscle cells transdifferentiating, phosphorous and calcium milieu, as well as matrix vesicles on the progress of VC. However, the underlying molecular mechanisms of VC need to be elucidated. Though there is no acknowledged effective therapeutic strategy to reverse or cure VC clinically, recent evidence has proved that VC is not a passive irreversible comorbidity but an active process regulated by many factors. Some available approaches targeting the underlying molecular mechanism provide promising prospects for the therapy of VC. This review aims to summarize the novel findings on molecular mechanisms and therapeutic interventions of VC, including the role of inflammatory responses, endoplasmic reticulum stress, mitochondrial dysfunction, iron homeostasis, metabolic imbalance, and some related signaling pathways on VC progression. We also conclude some recent studies on controversial interventions in the clinical practice of VC, such as calcium channel blockers, renin-angiotensin system inhibitions, statins, bisphosphonates, denosumab, vitamins, and ion conditioning agents.

Genetic regulation of iron homeostasis in sideropenic patients with mild COVID-19 disease under a new oral iron formulation: Lessons from a different perspective

Background

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) needs iron to replicate itself. Coronaviruses are able to upregulate Chop/Gadd153 and Arg1 genes, consequently leading to CD8 lymphocytes decrease, degradation of asparagine and decreased nitric oxide (NO), thus impairing immune response and antithrombotic functions. Little is known about regulation of genes involved in iron metabolism in paucisymptomatic patients with COVID-19 disease or in patients with iron deficiency treated with sucrosomial iron.

Methods

Whole blood was taken from the COVID-19 patients and from patients with sideropenic anemia, treated or not (control group) with iron supplementations. Enrolled patients were: affected by COVID19 under sucrosomal iron support (group A), affected by COVID-19 not under oral iron support (group B), iron deficiency not under treatment, not affected by COVID19 (control group). After RNA extraction and complementary DNA (cDNA) synthesis of Arg1, Hepcidin and Chop/Gadd153, gene expression from the 3 groups was measured by qRT-PCR. M2 macrophages were detected by cytofluorimetry using CD163 and CD14 markers.

Results

Forty patients with COVID-19 (group A), 20 patients with iron deficiency treated with sucrosomial iron (group B) and 20 patients with iron deficiency not under treatment (control group) were enrolled. In all the patients supported with oral sucrosomial iron, the gene expression of Chop, Arg1 and Hepcidin genes was lower than in sideropenic patients not supported with iron, M1 macrophages polarization and functional iron deficiency was also lower in group A and B, than observed in the control group.

Conclusions

New oral iron formulations, as sucrosomial iron, are able to influence the expression of genes like Chop and Arg1 and to influence M2 macrophage polarization mainly in the early phase of COVID-19 disease.

Lipocalin-2 in neutrophils induces ferroptosis in septic cardiac dysfunction via increasing labile iron pool of cardiomyocytes

Cardiac dysfunction is a common complication of sepsis with high mortality. The present study was designed to identify the effect of neutrophil-derived lipocalin-2 (LCN2) in septic cardiac dysfunction (SCD) and its potential mechanism. Wild-type (WT) and LCN2-knockout (LCN2 KO) mice were peritoneally injected with lipopolysaccharide (LPS) to induce SCD. The cardiac function was assessed 12 h after LPS injection by echocardiography. Cardiac tissue was harvested for the evaluation of malonaldehyde (MDA) and prostaglandin E synthase 2 (PTGS2) mRNA levels. LPS induced ferroptosis and SCD in mice. LCN2 deficiency attenuated cardiac injury post-LPS administration. In vitro, LCN2 expression in neutrophils increased in response to LPS. Ferroptosis of cardiomyocytes induced by conditioned medium (CM) from LPS-induced neutrophils of WT mice could be attenuated in CM from LPS-induced neutrophils of LCN2 KO mice. Exogenous LCN2 induced H9C2 cell ferroptosis via increasing labile iron pool (LIP). In conclusion, our results showed that LCN2 deficiency prevented heart dysfunction and ferroptosis in SCD mice and suggested that neutrophil-derived LCN2 might be a promising therapeutic target for SCD.

Computational Modeling of Macrophage Iron Sequestration during Host Defense against Aspergillus

Iron is essential to the virulence of Aspergillus species, and restricting iron availability is a critical mechanism of antimicrobial host defense. Macrophages recruited to the site of infection are at the crux of this process, employing multiple intersecting mechanisms to orchestrate iron sequestration from pathogens. To gain an integrated understanding of how this is achieved in aspergillosis, we generated a transcriptomic time series of the response of human monocyte-derived macrophages to Aspergillus and used this and the available literature to construct a mechanistic computational model of iron handling of macrophages during this infection. We found an overwhelming macrophage response beginning 2 to 4 h after exposure to the fungus, which included upregulated transcription of iron import proteins transferrin receptor-1, divalent metal transporter-1, and ZIP family transporters, and downregulated transcription of the iron exporter ferroportin. The computational model, based on a discrete dynamical systems framework, consisted of 21 3-state nodes, and was validated with additional experimental data that were not used in model generation. The model accurately captures the steady state and the trajectories of most of the quantitatively measured nodes. In the experimental data, we surprisingly found that transferrin receptor-1 upregulation preceded the induction of inflammatory cytokines, a feature that deviated from model predictions. Model simulations suggested that direct induction of transferrin receptor-1 (TfR1) after fungal recognition, independent of the iron regulatory protein-labile iron pool (IRP-LIP) system, explains this finding. We anticipate that this model will contribute to a quantitative understanding of iron regulation as a fundamental host defense mechanism during aspergillosis.

IMPORTANCE Invasive pulmonary aspergillosis is a major cause of death among immunosuppressed individuals despite the best available therapy. Depriving the pathogen of iron is an essential component of host defense in this infection, but the mechanisms by which the host achieves this are complex. To understand how recruited macrophages mediate iron deprivation during the infection, we developed and validated a mechanistic computational model that integrates the available information in the field. The insights provided by this approach can help in designing iron modulation therapies as anti-fungal treatments.

Transcriptomic Analysis in Human Macrophages Infected with Therapeutic Failure Clinical Isolates of Leishmania infantum

Leishmaniasis is one of the neglected tropical diseases with a worldwide distribution, affecting humans and animals. In the absence of an effective vaccine, current treatment is through the use of chemotherapy; however, existing treatments have frequent appearance of drug resistance and therapeutic failure (TF). The identification of factors that contribute to TF in leishmaniasis will provide the basis for a future therapeutic strategy more efficient for the control of this disease. In this article, we have evaluated the transcriptomic changes in the host cells THP-1 after infection with clinical Leishmania infantum isolates from leishmaniasis patients with TF. Our results show that distinct L. infantum isolates differentially modulate host cell response, inducing phenotypic changes that probably may account for parasite survival and TF of patients. Analysis of differential expression genes (DEGs), with a statistical significance threshold of a fold change ≥ 2 and a false discovery rate value ≤ 0.05, revealed a different number of DEGs according to the Leishmanialine. Globally, there was a similar number of genes up- and downregulated in all the infected host THP-1 cells, with exception of Hi-L2221, which showed a higher number of downregulated DEGs. We observed a total of 58 DEGs commonly modulated in all infected host cells, including upregulated (log₂FC ≥ 1) and downregulated (log₂FC ≤ -1) genes. Based on the results obtained from the analysis of RNA-seq, volcano plot, and GO enrichment analysis, we identified the most significant transcripts of relevance for their possible contribution to the TF observed in patients with leishmaniasis.

Heat Stress: Effects on Rumen Microbes and Host Physiology, and Strategies to Alleviate the Negative Impacts on Lactating Dairy Cows

Heat stress (HS) in dairy cows causes considerable losses in the dairy industry worldwide due to reduced animal performance, increased cases of metabolic disorders, altered rumen microbiome, and other health problems. Cows subjected to HS showed decreased ruminal pH and acetate concentration and an increased concentration of ruminal lactate. Heat-stressed cows have an increased abundance of lactate-producing bacteria such as Streptococcus and unclassified Enterobacteriaceae, and soluble carbohydrate utilizers such as Ruminobacter, Treponema, and unclassified Bacteroidaceae. Cellulolytic bacteria, especially Fibrobacteres, increase during HS due to a high heat resistance. Actinobacteria and Acetobacter, both acetate-producing bacteria, decreased under HS conditions. Rumen fermentation functions, blood parameters, and metabolites are also affected by the physiological responses of the animal during HS. Isoleucine, methionine, myo-inositol, lactate, tryptophan, tyrosine, 1,5-anhydro-D-sorbitol, 3-phenylpropionic acid, urea, and valine decreased under these conditions. These responses affect feed consumption and production efficiency in milk yield, growth rate, and reproduction. At the cellular level, activation of heat shock transcription factor (HSF) (located throughout the nucleus and the cytoplasm) and increased expression of heat shock proteins (HSPs) are the usual responses to cope with homeostasis. HSP70 is the most abundant HSP family responsible for the environmental stress response, while HSF1 is essential for increasing cell temperature. The expression of bovine lymphocyte antigen and histocompatibility complex class II (DRB3) is downregulated during HS, while HSP90 beta I and HSP70 1A are upregulated. HS increases the expression of the cytosolic arginine sensor for mTORC1 subunits 1 and 2, phosphorylation of mammalian target of rapamycin and decreases the phosphorylation of Janus kinase-2 (a signal transducer and activator of transcription factor-5). These changes in physiology, metabolism, and microbiomes in heat-stressed dairy cows require urgent alleviation strategies. Establishing control measures to combat HS can be facilitated by elucidating mechanisms, including proper HS assessment, access to cooling facilities, special feeding and care, efficient water systems, and supplementation with vitamins, minerals, plant extracts, and probiotics. Understanding the relationship between HS and the rumen microbiome could contribute to the development of manipulation strategies to alleviate the influence of HS. This review comprehensively elaborates on the impact of HS in dairy cows and introduces different alleviation strategies to minimize HS.

New Insights on Drug-Resistant Clinical Isolates of Leishmania infantum-Infected Human Macrophages as Determined by Comparative Transcriptome Analyses

Leishmaniasis is the second most important neglected tropical parasitic disease after malaria. This disease is distributed worldwide and can be present in a variety of clinical forms, depending on the parasite species and host's genetic background. As chemotherapy is the only effective weapon whose effectiveness is limited by the frequent appearance of drug resistance and therapeutic failure, new therapeutic strategies are required. To better understand the factors that contribute to therapeutic failure and drug resistance in leishmaniasis, we studied the transcriptomic changes in host THP-1 cells after infection with clinical Leishmania infantum isolates with different susceptibilities to antileishmanial drugs by RNA-seq. Analysis of the differentially expressed genes (DEGs) in infected host cells revealed variations in DEG numbers in the THP-1-infected cells depending on the Leishmania line. A key conclusion of this study is that the modulation of host cells is Leishmania line dependent. Gene ontology enrichment analyses of DEGs indicated that certain biological processes were modulated in the infected host cells, specifically related to cellular metabolism, immune response, defense response, signaling pathways, and cell proliferation and apoptosis. Furthermore, this study provides new potential therapeutic markers and insights into the THP-1 host transcriptomic changes that occur after late infection with drug-resistant L. infantum clinical isolates.

3-hydroxy butyrate dehydrogenase 2 deficiency aggravates systemic lupus erythematosus progression in a mouse model by promoting CD40 ligand demethylation

The implications of the CD40-CD40 ligand (CD40L) signaling pathway in systemic lupus erythematosus (SLE) were well documented, due to its important role among immune cells. Previous research found that 3-hydroxy butyrate dehydrogenase 2 (BDH2), a modulator of intracellular iron homeostasis and iron transportation promoted the pathogenic process of SLE by regulating the demethylation of cd70, cd11a, and cd40l genes among CD4 + T cells. The purpose of this study was to explore the role of BDH2 in oxidative damage-induced SLE. First, CD4 + T cells treated with H₂O₂ were injected into the tail vein of mice to establish a lupus model. CD40L knockdown significantly decreased CD40L expression on CD4 + T cells in the spleen of SLE mice. Compared with SLE model mice, the levels of serum anti-dsDNA antibody and urinary protein in the CD40L interference group were significantly decreased. CD40L knockdown alleviated the immune complex glomerulonephritis in syngeneic SLE mice. Moreover, the levels of IFN-γ and IL-2 were decreased. However, IL-4 and IL-10 levels were significantly upregulated in the serum of CD40L knockdown SLE mice, compared with SLE model mice. Accordingly, CD40L knockdown reduced Th1/Th2 percentage in SLE mice. Inhibiting the expression of BDH2 of CD4 + T cells promoted the demethylation of CD40L, while it inhibited cell proliferation, elevated oxidative stress through increased expression of CD40L, and thus, promoted the progress of SLE. Our results demonstrate that BDH2 aggravates the pathologic progression of SLE in mice, by increasing the demethylation level of CD40L among CD4 + T cells.

Evidence for the effect of soluble uric acid in augmenting endoplasmic reticulum stress markers in human peripheral blood mononuclear cells

There is evidence regarding the association of hyperuricemia with inflammatory disorders. Hence, it has been of particular interest to dissect the exact role of alteration in uric acid (UA) levels in the context of inflammation. Recently, the endoplasmic reticulum (ER) stress pathway has come into the forefront as a possible mechanism linking hyperuricemia to inflammation. Here, we intended to examine the role of UA in the presence or absence of a second stimulus, LPS, in human peripheral blood mononuclear cells (PBMCs), and analyzed ROS production as well as expression of ER stress markers: GRP78 and CHOP, and inflammatory cytokines.PBMCs were isolated using Ficoll gradient centrifugation from healthy volunteers. Cell viability was measured by MTT assay. PBMCs were treated with an increasing concentration of soluble UA (0, 5, 12, and 20 mg/dl) for 20 h, followed by the addition of 100 ng/mL of LPS or vehicle for another 4 h. Real time-PCR was performed to investigate the mRNA expression of GRP78, CHOP, TNF-α, IL-1β, and IL-6, and western blot was used to investigate the protein levels of GRP78 and CHOP. Moreover, ELISA was used to evaluate the protein levels of TNF-α, IL-1β, and IL-6. Finally, intracellular ROS production was determined using fluorescent probes (DCFH-DA).High concentrations of UA either alone or combined with LPS increased the protein levels of GRP78 and CHOP. On the other hand, LPS alone increased the protein levels of GRP78 and CHOP. However, there was no significant difference between the mRNA expression of GRP78, CHOP, TNF-α, IL-1β, and IL-6 when PBMCs were treated with UA. High concentrations of UA augmented LPS-stimulated IL-1β transcript and protein levels as well as TNF-α protein levels in PBMC culture. Moreover, high concentrations of UA along with LPS significantly increased intracellular ROS production.It seems that a high concentration of UA not only induces the protein levels of ER stress markers in PBMCs but also augments the impact of LPS on the levels of pro-inflammatory markers and ROS production.

Bdh2 Deficiency Promotes Endoderm-Biased Early Differentiation of Mouse Embryonic Stem Cells

3-hydroxybutyrate dehydrogenase-2 (Bdh2), a short-chain dehydrogenase, catalyzes a rate-limiting step in the biogenesis of the mammalian siderophore, playing a key role in iron homeostasis, energy metabolism and apoptosis. However, the function of Bdh2 in embryonic stem cells (ESCs) remains unknown. To gain insights into the role of Bdh2 on pluripotency and cell fate decisions of mouse ESCs, we generated Bdh2 homozygous knockout lines for both mouse advanced embryonic stem cell (ASC) and ESC using CRISPR/Cas9 genome editing technology. Bdh2 deficiency in both ASCs and ESCs had no effect on expression of core pluripotent transcription factors and alkaline phosphatase activity, suggesting dispensability of Bdh2 for self-renewal and pluripotency of ESCs. Interestingly, cells with Bdh2 deficiency exhibited potency of endoderm differentiation in vitro; with upregulated endoderm associated genes revealed by RNA-seq and RT-qPCR. We further demonstrate that Bdh2 loss inhibited expression of multiple methyltransferases (DNMTs) at both RNA and protein level, suggesting that Bdh2 may be essentially required to maintain DNA methylation in ASCs and ESCs. Overall, this study provides valuable data and resources for understanding how Bdh2 regulate earliest cell fate decision and DNA methylation in ASCs/ESCs.

Iron in immune cell function and host defense

The control over iron availability is crucial under homeostatic conditions and even more in the case of an infection. This results from diverse properties of iron: first, iron is an important trace element for the host as well as for the pathogen for various cellular and metabolic processes, second, free iron catalyzes Fenton reaction and is therefore producing reactive oxygen species as a part of the host defense machinery, third, iron exhibits important effects on immune cell function and differentiation and fourth almost every immune activation in turn impacts on iron metabolism and spatio-temporal iron distribution. The central importance of iron in the host and microbe interplay and thus for the course of infections led to diverse strategies to restrict iron for invading pathogens. In this review, we focus on how iron restriction to the pathogen is a powerful innate immune defense mechanism of the host called "nutritional immunity". Important proteins in the iron-host-pathogen interplay will be discussed as well as the influence of iron on the efficacy of innate and adaptive immunity. Recently described processes like ferritinophagy and ferroptosis are further covered in respect to their impact on inflammation and infection control and how they impact on our understanding of the interaction of host and pathogen.

Gene expression of the heat stress response in bovine peripheral white blood cells and milk somatic cells in vivo

Heat stress in dairy cattle leads to reduction in feed intake and milk production as well as the induction of many physiological stress responses. The genes implicated in the response to heat stress in vivo are not well characterised. With the aim of identifying such genes, an experiment was conducted to perform differential gene expression in peripheral white blood cells and milk somatic cells in vivo in 6 Holstein Friesian cows in thermoneutral conditions and in 6 Holstein Friesian cows exposed to a short-term moderate heat challenge. RNA sequences from peripheral white blood cells and milk somatic cells were used to quantify full transcriptome gene expression. Genes commonly differentially expressed (DE) in both the peripheral white blood cells and in milk somatic cells were associated with the cellular stress response, apoptosis, oxidative stress and glucose metabolism. Genes DE in peripheral white blood cells of cows exposed to the heat challenge compared to the thermoneutral control were related to inflammation, lipid metabolism, carbohydrate metabolism and the cardiovascular system. Genes DE in milk somatic cells compared to the thermoneutral control were involved in the response to stress, thermoregulation and vasodilation. These findings provide new insights into the cellular adaptations induced during the response to short term moderate heat stress in dairy cattle and identify potential candidate genes (BDKRB1 and SNORA19) for future research.

Iron in infection and immunity

Iron is an essential micronutrient for virtually all living cells. In infectious diseases, both invading pathogens and mammalian cells including those of the immune system require iron to sustain their function, metabolism and proliferation. On the one hand, microbial iron uptake is linked to the virulence of most human pathogens. On the other hand, the sequestration of iron from bacteria and other microorganisms is an efficient strategy of host defense in line with the principles of 'nutritional immunity'. In an acute infection, host-driven iron withdrawal inhibits the growth of pathogens. Chronic immune activation due to persistent infection, autoimmune disease or malignancy however, sequesters iron not only from infectious agents, autoreactive lymphocytes and neoplastic cells but also from erythroid progenitors. This is one of the key mechanisms which collectively result in the anemia of chronic inflammation. In this review, we highlight the most important interconnections between iron metabolism and immunity, focusing on host defense against relevant infections and on the clinical consequences of anemia of inflammation.

BDH2 triggers ROS-induced cell death and autophagy by promoting Nrf2 ubiquitination in gastric cancer

Background

3-Hydroxy butyrate dehydrogenase 2 (BDH2) is a short-chain dehydrogenase/reductase family member that plays a key role in the development and pathogenesis of human cancers. However, the role of BDH2 in gastric cancer (GC) remains largely unclear. Our study aimed to ascertain the regulatory mechanisms of BDH2 in GC, which could be used to develop new therapeutic strategies.

Methods

Western blotting, immunohistochemistry, and RT-PCR were used to investigate the expression of BDH2 in GC specimens and cell lines. Its correlation with the clinicopathological characteristics and prognosis of GC patients was analysed. Functional assays, such as CCK-8 and TUNEL assays, transmission electron microscopy, and an in vivo tumour growth assay, were performed to examine the proliferation, apoptosis, and autophagy of GC cells. Related molecular mechanisms were clarified by luciferase reporter, coimmunoprecipitation, and ubiquitination assays.

Results

BDH2 was markedly downregulated in GC tissues and cells, and the low expression of BDH2 was associated with poor survival of GC patients. Functionally, BDH2 overexpression significantly induced apoptosis and autophagy in vitro and in vivo. Mechanistically, BDH2 promoted Keap1 interaction with Nrf2 to increase the ubiquitination level of Nrf2. Ubiquitination/degradation of Nrf2 inhibited the activity of ARE to increase accumulation of reactive oxygen species (ROS), thereby inhibiting the phosphorylation levels of Akt^Ser473 and mTOR^Ser2448.

Conclusions

Our study indicates that BDH2 is an important tumour suppressor in GC. BDH2 regulates intracellular ROS levels to mediate the PI3K/Akt/mTOR pathway through Keap1/Nrf2/ARE signalling, thereby inhibiting the growth of GC.

The Effects of Human BDH2 on the Cell Cycle, Differentiation, and Apoptosis and Associations with Leukemia Transformation in Myelodysplastic Syndrome

Iron overload is related to leukemia transformation in myelodysplastic syndrome (MDS) patients. Siderophores help to transport iron. Type 2-hydroxybutyrate dehydrogenase (BDH2) is a rate-limiting factor in the biogenesis of siderophores. Using qRT-PCR, we analyze BDH2mRNA expression in the bone marrow (BM) of 187 MDS patients, 119 de novo acute myeloid leukemia (AML) patients, and 43 lymphoma patients with normal BM. Elevated BDH2mRNA expression in BM is observed in MDS patients (n = 187 vs. 43, normal BM; P = 0.009), and this is related to ferritin levels. Patients with higher BDH2 expression show a greater risk of leukemia progression (15.25% vs. 3.77%, lower expression; P = 0.017) and shorter leukemia-free-survival (medium LFS, 9 years vs. 7 years; P = 0.024), as do patients with a ferritin level ≥350 ng/mL. Additionally, we investigate the mechanisms related to the prognostic ability of BDH2 by using BDH2-KD THP1. The cell cycle analysis, surface markers, and special stain studies indicate that BDH2-KD induces differentiation and decreases the growth rate of THP1 cells, which is associated with the retardation of the cell cycle. Moreover, many genes, including genes related to mitochondrial catabolism, oncogenes, tumor suppressor genes, and genes related to cell differentiation and proliferation influence BDH2-KD THP1 cells. Herein, we demonstrate that BDH2 is involved in cell cycle arrest and the inhibition of differentiation in malignant cells. Furthermore, the high BDH2 expression in MDS patients could be suggestive of a poor prognostic factor. This study provides a foundation for further research on the roles of BDH2 and iron metabolism in the pathogenesis of MDS.

Inactivation of 3-hydroxybutyrate dehydrogenase type 2 promotes proliferation and metastasis of nasopharyngeal carcinoma by iron retention

Background

3-Hydroxybutyrate dehydrogenase type 2 (BDH2) is known to catalyse a rate-limiting step in the biogenesis of the mammalian siderophore and regulate intracellular iron metabolism. Here we aim to explore the expression and possible function of BDH2 in nasopharyngeal carcinoma (NPC).

Methods

The transcription and protein expression of BDH2 in NPC were determined by both real-time RT-PCR and immunohistochemistry staining assays. Cell proliferation, migration and invasion were evaluated by MTT assay, wound-healing assay and Transwell assay, respectively. The profile of genes regulated by restoring BDH2 expression in NPC cells was analysed by cDNA microarray. The level of iron in NPC cells was detected by iron colorimetric assay.

Results

The expression of BDH2 was significantly downregulated in NPC. Ectopic expression of BDH2 inhibited NPC cell proliferation and colony formation. Meanwhile, BDH2 suppressed the migration and invasion of NPC cells by reversing the epithelial–mesenchymal transition (EMT). In addition, a higher level of BDH2 decreased the growth and metastasis of NPC cells via reducing intracellular iron level.

Conclusions

Our findings suggest that BDH2 may be a candidate tumour-suppressor gene in NPC. Decreasing intracellular iron could be an effective therapeutic approach for NPC.

Age modulates liver responses to asparaginase-induced amino acid stress in mice

Asparaginase is an amino acid-depleting agent used to treat blood cancers. Metabolic complications due to asparaginase affect liver function in humans. To examine how the liver response to asparaginase changes during maturity to adulthood, here we treated juvenile (2-week), young adult (8-week), and mature adult (16-week) mice with drug or excipient for 1 week and conducted RNA-Seq and functional analyses. Asparaginase reduced body growth and liver mass in juveniles but not in the adult animals. Unbiased exploration of the effect of asparaginase on the liver transcriptome revealed that the integrated stress response (ISR) was the only molecular signature shared across the ages, corroborating similar eukaryotic initiation factor 2 phosphorylation responses to asparaginase at all ages. Juvenile livers exhibited steatosis and iron accumulation following asparaginase exposure along with a hepatic gene signature indicating that asparaginase uniquely affects lipid, cholesterol, and iron metabolism in juvenile mice. In contrast, asparaginase-treated adult mice displayed greater variability in liver function, which correlated with an acute-phase inflammatory response gene signature. Asparaginase-exposed adults also had a serine/glycine/one-carbon metabolism gene signature in liver that corresponded with reduced circulating glycine and serine levels. These results establish the ISR as a conserved response to asparaginase-mediated amino acid deprivation and provide new insights into the relationship between the liver transcriptome and hepatic function upon asparaginase exposure.

BDH2 is downregulated in hepatocellular carcinoma and acts as a tumor suppressor regulating cell apoptosis and autophagy

BDH2 is a short-chain dehydrogenase/reductase family member involved in several biological and pathological processes, including the utilization of cytosolic ketone bodies, immunocyte regulation and tumor progression. In this study, we first revealed that BDH2 was downregulated in HCC tissues by qRT-PCR and immunohistochemistry analysis and that low BHD2 expression was significantly associated with poor overall survival, poor tumor differentiation, increased tumor size, venous invasion and an advanced BCLC stage. Moreover, the results of a univariate analysis and multivariate analysis revealed that BDH2 may be regarded as an independent prognostic marker. As a member of a gene family involved in ketone metabolism, BDH2 upregulated the level of β-HB in liver cells as well as the level of H3 histone acetylation. Functional analysis showed that BDH2 expression inhibited tumor cell growth, proliferation and migration. The results of the mechanistic analysis revealed that BDH2 induced mitochondrial apoptosis and inhibited autophagy through the unfolded protein response. Therefore, BDH2 may be a new HCC prognostic marker and a useful treatment target.

Endoplasmic reticulum stress signalling - from basic mechanisms to clinical applications

The endoplasmic reticulum (ER) is a membranous intracellular organelle and the first compartment of the secretory pathway. As such, the ER contributes to the production and folding of approximately one‐third of cellular proteins, and is thus inextricably linked to the maintenance of cellular homeostasis and the fine balance between health and disease. Specific ER stress signalling pathways, collectively known as the unfolded protein response (UPR), are required for maintaining ER homeostasis. The UPR is triggered when ER protein folding capacity is overwhelmed by cellular demand and the UPR initially aims to restore ER homeostasis and normal cellular functions. However, if this fails, then the UPR triggers cell death. In this review, we provide a UPR signalling‐centric view of ER functions, from the ER's discovery to the latest advancements in the understanding of ER and UPR biology. Our review provides a synthesis of intracellular ER signalling revolving around proteostasis and the UPR, its impact on other organelles and cellular behaviour, its multifaceted and dynamic response to stress and its role in physiology, before finally exploring the potential exploitation of this knowledge to tackle unresolved biological questions and address unmet biomedical needs. Thus, we provide an integrated and global view of existing literature on ER signalling pathways and their use for therapeutic purposes.

Validation of Osteogenic Properties of Cytochalasin D by High-Resolution RNA-Sequencing in Mesenchymal Stem Cells Derived from Bone Marrow and Adipose Tissues

Differentiation of mesenchymal stromal/stem cells (MSCs) involves a series of molecular signals and gene transcription events required for attaining cell lineage commitment. Modulation of the actin cytoskeleton using cytochalasin D (CytoD) drives osteogenesis at early timepoints in bone marrow-derived MSCs and also initiates a robust osteogenic differentiation program in adipose tissue-derived MSCs. To understand the molecular basis for these pronounced effects on osteogenic differentiation, we investigated global changes in gene expression in CytoD-treated murine and human MSCs by high-resolution RNA-sequencing (RNA-seq) analysis. A three-way bioinformatic comparison between human adipose tissue-derived MSCs (hAMSCs), human bone marrow-derived MSCs (hBMSCs), and mouse bone marrow-derived MSCs (mBMSCs) revealed significant upregulation of genes linked to extracellular matrix organization, cell adhesion and bone metabolism. As anticipated, the activation of these differentiation-related genes is accompanied by a downregulation of nuclear and cell cycle-related genes presumably reflecting cytostatic effects of CytoD. We also identified eight novel CytoD activated genes-VGLL4, ARHGAP24, KLHL24, RCBTB2, BDH2, SCARF2, ACAD10, HEPH-which are commonly upregulated across the two species and tissue sources of our MSC samples. We selected the Hippo pathway-related VGLL4 gene, which encodes the transcriptional co-factor Vestigial-like 4, for further study because this pathway is linked to osteogenesis. VGLL4 small interfering RNA depletion reduces mineralization of hAMSCs during CytoD-induced osteogenic differentiation. Together, our RNA-seq analyses suggest that while the stimulatory effects of CytoD on osteogenesis are pleiotropic and depend on the biological state of the cell type, a small group of genes including VGLL4 may contribute to MSC commitment toward the bone lineage.

Downregulation of BDH2 modulates iron homeostasis and promotes DNA demethylation in CD4+ T cells of systemic lupus erythematosus

DNA hypomethylation plays an important role in the pathogenesis of systemic lupus erythematosus (SLE). Here we investigated whether 3-hydroxy butyrate dehydrogenase 2 (BDH2), a modulator of intracellular iron homeostasis, was involved in regulating DNA hypomethylation and hyper-hydroxymethylation in lupus CD4⁺ T cells. Our results showed that BDH2 expression was decreased, intracellular iron was increased, global DNA hydroxymethylation level was elevated, while methylation level was reduced in lupus CD4⁺ T cells compared with healthy controls. The decreased BDH2 contributed to DNA hyper-hydroxymethylation and hypomethylation via increasing intracellular iron in CD4⁺ T cells, which led to overexpression of immune related genes. Moreover, we showed that BDH2 was the target gene of miR-21. miR-21 promoted DNA demethylation in CD4⁺ T cells through inhibiting BDH2 expression. Our data demonstrated that the dysregulation of iron homeostasis in CD4⁺ T cells induced by BDH2 deficiency contributes to DNA demethylation and self-reactive T cells in SLE.

Endoplasmic Reticulum Stress and Apoptosis Triggered by Sub-Chronic Lead Exposure in Mice Spleen: a Histopathological Study

Lead (Pb) is an environmental oncogenic metal that induces immunotoxicity and anaemia. Emerging evidence has linked Pb toxicity with endoplasmic reticulum-driven apoptosis and autophagy. Glucose-regulated protein of 78 kDa (Grp78 or binding immunoglobulin protein (BiP)), a master endoplasmic reticulum chaperone, drives macrophage activation and regulates protein folding and calcium flux in response to heavy metals. The spleen may be involved in Pb poisoning due to its crucial role in erythrocatheresis and immune response, although there are no data to support this theory. Here, we found haematic and histopathological changes in the spleen of mice exposed to medium doses of Pb acetate (200 ppm-1 mM) in drinking water for 45 days. Pb deposition was also detected in organs such as the liver, kidney, brain, bone, blood and faeces, indicating an accumulation of this metal despite relatively short exposure time. Blood Pb content (BBL) reached 21.6 μg/dL; echinocytes and poikilocytes were found in Pb smears of treated group. Inside the spleen, higher Fe(II) and Fe(III) deposits inside macrophages were observed. Grp78 immunostaining, weakly expressed in spleen cells of control mice, after Pb exposure was specifically restricted to macrophages and megakaryocytes of the marginal zone of red pulp. Furthermore, Pb exposure induced superoxide dismutase 1 (SOD1) expression, cleaved caspase-3 and p62/SQSTM1, consistent with oxidative stress, apoptosis and dysregulated autophagy in spleen compartments. We suggest that even at a middle dose, oral Pb intake induces oxidant iron deposition in the spleen and that this may trigger sustained Grp78 redistribution to cells, thus leading to oxidative and autophagy dysfunction as early local reactions to this dangerous metal.

Iron- and Hepcidin-Independent Downregulation of the Iron Exporter Ferroportin in Macrophages during Salmonella Infection

Retention of iron in tissue macrophages via upregulation of hepcidin (HAMP) and downregulation of the iron exporter ferroportin (FPN) is thought to participate in the establishment of anemia of inflammation after infection. However, an upregulation of FPN has been proposed to limit macrophages iron access to intracellular pathogens. Therefore, we studied the iron homeostasis and in particular the regulation of FPN after infection with Salmonella enterica serovar Typhimurium in mice presenting tissue macrophages with high iron (AcB61), basal iron (A/J and wild-type mice), or low iron (Hamp knock out, Hamp^-/-) levels. The presence of iron in AcB61 macrophages due to extravascular hemolysis and strong erythrophagocytosis activity favored the proliferation of Salmonella in the spleen and liver with a concomitant decrease of FPN protein expression. Despite systemic iron overload, no or slight increase in Salmonella burden was observed in Hamp^-/- mice compared to controls. Importantly, FPN expression at both mRNA and protein levels was strongly decreased during Salmonella infection in Hamp^-/- mice. The repression of Fpn mRNA was also observed in Salmonella-infected cultured macrophages. In addition, the downregulation of FPN was associated with decreased iron stores in both the liver and spleen in infected mice. Our findings show that during Salmonella infection, FPN is repressed through an iron and hepcidin-independent mechanism. Such regulation likely provides the cellular iron indispensable for the growth of Salmonella inside the macrophages.

The Effects of First-Line Anti-Tuberculosis Drugs on the Actions of Vitamin D in Human Macrophages

Tuberculosis (TB) is a major global health problem. Patients with TB have a high rate of vitamin D deficiency, both at diagnosis and during the course of treatment with anti-tuberculosis drugs. Although data on the efficacy of vitamin D supplementation on Mycobacterium tuberculosis (Mtb) clearance is uncertain from randomized controlled trials (RCTs), vitamin D enhances the expression of the anti-microbial peptide human cathelicidin (hCAP18) in cultured macrophages in vitro. One possible explanation for the mixed (primarily negative) results of RCTs examining vitamin D treatment in TB infection is that anti-TB drugs given to enrolled subjects may impact actions of vitamin D to enhance cathelicidin in macrophages. To address this hypothesis, human macrophage-like monocytic (THP-1) cells were treated with varying doses of first-line anti-tuberculosis drugs in the presence of the active form of vitamin D, 1N1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃). The expression of hCAP18 was determined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). 1,25(OH)₂D₃ strongly induced expression of hCAP18 mRNA in THP-1 cells (fold-change from control). The combination of the standard 4-drug TB therapy (isoniazid, rifampicin, pyrazinamide and ethambutol) in the cultured THP-1 cells demonstrated a significant decrease of hCAP18 mRNA at the dosage of 10 ug/mL. In 31 subjects with newly diagnosed drug-sensitive TB randomized to either high-dose vitamin D₃ (1.2 million IU over 8 weeks, n=13) versus placebo (n=18), there was no change from baseline to week 8 in hCAP18 mRNA levels in peripheral blood mononuclear cells or in plasma concentrations of LL-37, the protein product of hCAP18.These data suggest that first-line anti-TB drugs may alter the vitamin D-dependent increase in hCAP18 and LL-37 human macrophages.