Impact of Hydroxyglutarate on Dendritic Cell Activation

Tumor development is commonly associated with genetic alterations such as activation of oncogenes or the silencing of tumor suppressor genes. Recently point mutations in genes encoding isocitrate dehydrogenase (IDH) have gained substantial interest in glioma classification. IDH mutations are also frequently found in neoplasias including acute myeloid leukemia (AML). Mutated IDH aquires the function to produce the oncometabolite D-2-hydroxyglutarate (D-HG). D-HG levels in the tissue of glioma patients can reach concentrations up to 35mM. Nevertheless, little is known on the impact of D-HG on non-malignant human immune cells. In the present work, we compared the effect of both HG enantiomers, D-HG and L-2-Hydroxyglutarate (L-HG) on dendritic cell (DC) maturation and activation, and found similar effects with both enantiomers. We also analyzed the impact of D-HG on the respiration of DCs and two glioblastoma cell lines. We found that D-HG was taken up by LPS-stimulated DCs. Furthermore, the presence of D-HG during maturation and activation of DCs strongly affected the production of IL-12. Especially when DCs were treated with D-HG during the entire maturation process, the IL-12 production was extremely reduced. To elucidate the mechanism by which D-HG modulates IL-12 production, we studied the principal components of the Toll-like receptor 4 signaling pathway involved in IL-12 p70 production (NF-κB, HIF-α, PI3-kinase pathway components). However, we found no significant effect of D-HG treatment on any of these pathways after 1hr or 24hrs of incubation. As we found an increase of GPR109A expression after LPS stimulation, we studied a possible involvement of this receptor but found no significant relation between IL-12 production and the reported GPR109A ligand, niacin. Cyclic adenosine monophosphate (cAMP) has been described to be involved in DC function. We found significant reduction of IL-12 production by the treatment of DCs with cAMP and the cAMP-inducing-factor forskolin. However, due to technical problems, we could not detect cAMP in DCs. As several reports state a possible relation between cAMP signaling pathways and mitochondrial respiration, we analyzed the impact of D-HG on mitochondrial respiration of LPS-stimulated DCs. We observed an inhibition of routine respiration caused by LPS, whereas pre-treatment with D-HG blocked this LPS effect. As treatment with oligomycin and rotenone (inhibitors of mitochondrial respiration) did not recover IL-12 suppression, the impact of HG on respiration alone is not sufficient to explain the suppressive effect of HG. To further analyze the effect of D-HG on mitochondrial respiration we utilized an inhibitor of mitochondrial calcium efflux, cyclosporine A (CsA). We noticed an increase of IL-12 levels after CsA treatment compared with DCs activated without CsA treatment. Combination of CsA and D-HG in LPS-stimulated DCs partially rescued IL-12 levels caused by D-HG treatment. During high resolution respirometry studies we observed a delayed reduction of routine respiration 2hrs after CsA treatment. Also, we found a modest increase of respiratory chain complex expression in stimulated DCs treated with D-HG (complex I and II). Moreover, lactate secretion studies showed an increase of lactate levels by LPS. D-HG was able to block this increase. These observations point towards the capacity of D-HG to interfere with the metabolic shift from oxidative phosphorylation into glycolysis promoted by LPS. This could also explain the suppressive effect of D-HG on IL-12 production. IDH mutations are associated with glioma development and prognosis. Nevertheless the effect of D-HG on mitochondrial respiration of glioma cell lines is poorly documented. In the present work, we found no consistent effect on mitochondrial respiration by D-HG in two glioma cell lines. Furthermore, we investigated global effects of HG on DCs by RNAseq analyses. Surprisingly most genes were similarily regulated by HG and our control substance di-ketoglutarate most likely due to its close structural similarity. Only 6 genes were upregulated and 3 genes were downregulated by HG. Further investigations have to be performed to investigate the link between the identified genes and DC function

D-2-hydroxyglutarate interferes with HIF-1α stability skewing T-cell metabolism towards oxidative phosphorylation and impairing Th17 polarization

D-2-hydroxyglutarate (D-2HG) is released by various types of malignant cells including acute myeloid leukemia (AML) blasts carrying isocitrate dehydrogenase (IDH) gain-of-function mutations. D-2HG acting as an oncometabolite promotes proliferation, anoikis, and differentiation block of hematopoietic cells in an autocrine fashion. However, prognostic impact of IDH mutations and high D-2HG levels remains controversial and might depend on the overall mutational context. An increasing number of studies focus on the permissive environment created by AML blasts to promote immune evasion. Impact of D-2HG on immune cells remains incompletely understood. Here, we sought out to investigate the effects of D-2HG on T-cells as key mediators of anti-AML immunity. D-2HG was efficiently taken up by T-cells in vitro, which is in line with high 2-HG levels measured in T-cells isolated from AML patients carrying IDH mutations. T-cell activation was slightly impacted by D-2HG. However, D-2HG triggered HIF-1a protein destabilization resulting in metabolic skewing towards oxidative phosphorylation, increased regulatory T-cell (Treg) frequency, and reduced T helper 17 (Th17) polarization. Our data suggest for the first time that D-2HG might contribute to fine tuning of immune responses

The Specialized Roles in Carotenogenesis and Apocarotenogenesis of the Phytoene Synthase Gene Family in Saffron

Crocus sativus stigmas are the main source of crocins, which are glucosylated apocarotenoids derived from zeaxanthin cleavage that give saffron its red color. Phytoene synthase (PSY) mediates the first committed step in carotenoid biosynthesis in plants. Four PSY genes encoding functional enzymes were isolated from saffron. All the proteins were localized in plastids, but the expression patterns of each gene, CsPSY1a, CsPSY1b, CsPSY2, and CsPSY3, in different saffron tissues and during the development of the stigma showed different tissue specialization. The CsPSY2 transcript was primarily detected in the stigmas where it activates and stimulates the accumulation of crocins, while its expression was very low in other tissues. In contrast, CsPSY1a and CsPSY1b were mainly expressed in the leaves, but only CsPSY1b showed stresslight regulation. Interestingly, CsPSY1b showed differential expression of two alternative splice variants, which differ in the intron retention at their 50 UTRs, resulting in a reduction in their expression levels. In addition, the CsPSY1a and CsPSY1b transcripts, together with the CsPSY3 transcript, were induced in roots under different stress conditions. The CsPSY3 expression was high in the root tip, and its expression was associated with mycorrhizal colonization and strigolactone production. CsPSY3 formed a separate branch to the stress-specific Poaceae homologs but was closely related to the dicot PSY3 enzymes

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

First report of begomoviruses infecting Cucumis sativus L. in North America and identification of a proposed new begomovirus species

Background Members of the Begomovirus genus are phytopathogens that infect dicotyledonous plants, producing economic losses in tropical and subtropical regions. To date, only seven species of begomoviruses (BGVs) infecting cucumber have been described. Most cucumber infections were reported in South Asia. In the Americas, begomoviral infections affecting cucumber are scarce; just one report of begomovirus has been described in South America. The presence of whitefly and typical symptoms of viral infections observed in a cucumber field in Colima, Mexico, suggested that plants in this field were affected by BGVs. Methods To identify the BGVs infecting cucumber, we performed a high-throughput sequencing and compared the assembled contigs against the GenBank nucleic acid sequence database. To confirm the presence of viruses in cucumber samples, we performed a PCR detection using specific oligonucleotides. We cloned and sequenced by Sanger method the complete genome of a potential new begomovirus. Begomovirus species demarcation was performed according to the International Committee on Taxonomy of Viruses. The evolutionary relationship of the new virus was inferred using phylogenetic and recombination analyses. Results We identified five species of begomovirus infecting plants in a field. None of these have been previously reported infecting cucumber. One of the five species of viruses here reported is a new begomovirus species. Cucumber chlorotic leaf virus, the new species, is a bipartite begomovirus that has distinctive features of viruses belonging to the squash leaf curl virus clade. Conclusions The findings here described represent the first report of begomoviral infection affecting cucumber plants in North America. Previous to this report, only seven begomovirus species have been reported in the world, here we found five species infecting cucumber plants in a small sample suggesting that cucumber is vulnerable to BGVs. One of these viruses is a new species of begomovirus which is the first begomovirus originally isolated from the cucumber. The findings of this report could help to develop strategies to fight the begomoviral infections that affect cucumber crops

A Lineage of Begomoviruses Encode Rep and AC4 Proteins of Enigmatic Ancestry: Hints on the Evolution of Geminiviruses in the New World

The begomoviruses (BGVs) are plant pathogens that evolved in the Old World during the Cretaceous and arrived to the New World (NW) in the Cenozoic era. A subgroup of NW BGVs, the “Squash leaf curl virus (SLCV) lineage” (S-Lin), includes viruses with unique characteristics. To get clues on the evolutionary origin of this lineage, a search for divergent members was undertaken. Four novel BGVs were characterized, including one that is basal to the group. Comparative analyses led to discover a ~670 bp genome module that is nearly exclusive of this lineage, encompassing the replication origin, the AC4 gene, and 480 bp of the Rep gene. A similar DNA module was found in two curtoviruses, hence suggesting that the S-Lin ancestor acquired its distinctive genomic segment by recombination with a curtovirus. This hypothesis was definitely disproved by an in-depth sequence analysis. The search for homologs of S-Lin Rep uncover the common origin of Rep proteins encoded by diverse Geminiviridae genera and viral “fossils” integrated at plant genomes. In contrast, no homolog of S-Lin Rep was found in public databases. Consequently, it was concluded that the SLCV clade ancestor evolved by a recombination event between a primitive NW BGV and a virus from a hitherto unknown lineage