Oxidative stress, defective proteostasis and immunometabolic complications in critically ill patients.

Oxidative stress (OS) develops in critically ill patients as a metabolic consequence of the immunoinflammatory and degenerative processes of the tissues. These induce increased and/or dysregulated fluxes of reactive species enhancing their pro-oxidant activity and toxicity. At the same time, OS sustains its own inflammatory and immunometabolic pathogenesis, leading to a pervasive and vitious cycle of events that contribute to defective immunity, organ dysfunction and poor prognosis. Protein damage is a key player of these OS effects; it generates increased levels of protein oxidation products and misfolded proteins in both the cellular and extracellular environment, and contributes to forms DAMPs and other proteinaceous material to be removed by endocytosis and proteostasis processes of different cell types, as endothelial cells, tissue resident monocytes-macrophages and peripheral immune cells. An excess of OS and protein damage in critical illness can overwhelm such cellular processes ultimately interfering with systemic proteostasis, and consequently with innate immunity and cell death pathways of the tissues thus sustaining organ dysfunction mechanisms. Extracorporeal therapies based on biocompatible/bioactive membranes and new adsorption techniques may hold some potential in reducing the impact of OS on the defective proteostasis of patients with critical illness. These can help neutralizing reactive and toxic species, also removing solutes in a wide spectrum of molecular weights thus improving proteostasis and its immunometabolic corelates. Pharmacological therapy is also moving steps forward which could help to enhance the efficacy of extracorporeal treatments. This narrative review article explores the aspects behind the origin and pathogenic role of OS in intensive care and critically ill patients, with a focus on protein damage as a cause of impaired systemic proteostasis and immune dysfunction in critical illness.

Subcellular distribution and Nrf2/Keap1-interacting properties of Glutathione S-transferase P in hepatocellular carcinoma.

The oncogene and drug metabolism enzyme glutathione S-transferase P (GSTP) is also a GSH-dependent chaperone of signal transduction and transcriptional proteins with key role in liver carcinogenesis. In this study, we explored this role of GSTP in hepatocellular carcinoma (HCC) investigating the possible interaction of this protein with one of its transcription factor and metronome of the cancer cell redox, namely the nuclear factor erythroid 2-related factor 2 (Nrf2). Expression, cellular distribution, and function as glutathionylation factor of GSTP1-1 isoform were investigated in the mouse model of N-nitrosodiethylamine (DEN)-induced HCC and in vitro in human HCC cell lines. The physical and functional interaction of GSTP protein with Nrf2 and Keap1 were investigated by immunoprecipitation and gene manipulation experiments. GSTP protein increased its liver expression, enzymatic activity and nuclear levels during DEN-induced tumor development in mice; protein glutathionylation (PSSG) was increased in the tumor masses. Higher levels and a preferential nuclear localization of GSTP protein were also observed in HepG2 and Huh-7 hepatocarcinoma cells compared to HepaRG non-cancerous cells, along with increased basal and Ebselen-stimulated levels of free GSH and PSSG. GSTP activity inhibition with the GSH analogue EZT induced apoptotic cell death in HCC cells. Hepatic Nrf2 and c-Jun, two transcription factors involved in GSTP expression and GSH biosynthesis, were induced in DEN-HCC compared to control animals; the Nrf2 inhibitory proteins Keap1 and ß-TrCP also increased and oligomeric forms of GSTP co-immunoprecipitated with both Nrf2 and Keap1. Nrf2 nuclear translocation and ß-TrCP expression also increased in HCC cells, and GSTP transfection in HepaRG cells induced Nrf2 activation. In conclusion, GSTP expression and subcellular distribution are modified in HCC cells and apparently contribute to the GSH-dependent reprogramming of the cellular redox in this type of cancer directly influencing the transcriptional system Nrf2/Keap1.

Induction of Vesicular Trafficking and JNK-Mediated Apoptotic Signaling in Mononuclear Leukocytes Marks the Immuno-Proteostasis Response to Uremic Proteins.

INTRODUCTION: Uremic retention solutes have been alleged to induce the apoptotic program of different cell types, including peripheral blood mononuclear leukocytes (PBL), which may contribute to uremic leukopenia and immune dysfunction. METHODS: The molecular effects of these solutes were investigated in uremic PBL (u-PBL) and mononuclear cell lines (THP-1 and K562) exposed to the high molecular weight fraction of uremic plasma (u-HMW) prepared by in vitro ultrafiltration with 50 kDa cut-off microconcentrators. RESULTS: u-PBL show reduced cell viability and increased apoptotic death compared to healthy control PBL (c-PBL). u-HMW induce apoptosis both in u-PBL and c-PBL, as well as in mononuclear cell lines, also stimulating cellular H2O2 formation and secretion, IRE1-α-mediated endoplasmic reticulum stress signaling, and JNK/cJun pathway activation. Also, u-HMW induce autophagy in THP-1 monocytes. u-PBL were characterized by the presence in their cellular proteome of the main proteins and carbonylation targets of u-HMW, namely albumin, transferrin, and fibrinogen, and by the increased expression of receptor for advanced glycation end-products, a scavenger receptor with promiscuous ligand binding properties involved in leukocyte activation and endocytosis. CONCLUSIONS: Large uremic solutes induce abnormal endocytosis and terminal alteration of cellular proteostasis mechanisms in PBL, including UPR/ER stress response and autophagy, ultimately activating the JNK-mediated apoptotic signaling of these cells. These findings describe the suicidal role of immune cells in facing systemic proteostasis alterations of kidney disease patients, a process that we define as the immuno-proteostasis response of uremia.

Accumulation of 4-Hydroxynonenal Characterizes Diabetic Fat and Modulates Adipogenic Differentiation of Adipose Precursor Cells.

Redox imbalance in fat tissue appears to be causative of impaired glucose homeostasis. This "proof-of-concept" study investigated whether the peroxidation by-product of polyunsaturated n-6 fatty acids, namely 4-hydroxynonenal (4-HNE), is formed by, and accumulates in, the adipose tissue (AT) of obese patients with type 2 diabetes (OBT2D) as compared with lean, nondiabetic control subjects (CTRL). Moreover, we studied the effects of 4-HNE on the cell viability and adipogenic differentiation of adipose-derived stem cells (ASCs). Protein-HNE adducts in subcutaneous abdominal AT (SCAAT) biopsies from seven OBT2D and seven CTRL subjects were assessed using Western blot. The effects of 4-HNE were then studied in primary cultures of ASCs, focusing on cell viability, adipogenic differentiation, and the "canonical" Wnt and MAPK signaling pathways. When compared with the controls, the OBT2D patients displayed increased HNE-protein adducts in the SCAAT. The exposure of ASCs to 4-HNE fostered ROS production and led to a time- and concentration-dependent decrease in cell viability. Notably, at concentrations that did not affect cell viability (1 µM), 4-HNE hampered adipogenic ASCs' differentiation through a timely-regulated activation of the Wnt/ß-catenin, p38MAPK, ERK1/2- and JNK-mediated pathways. These "hypothesis-generating" data suggest that the increased accumulation of 4-HNE in the SCAAT of obese patients with type 2 diabetes may detrimentally affect adipose precursor cell differentiation, possibly contributing to the obesity-associated derangement of glucose homeostasis.

Platelets Rich Plasma Increases Antioxidant Defenses of Tenocytes via Nrf2 Signal Pathway.

Tendinopathies are common disabling conditions in equine and human athletes. The etiology is still unclear, although reactive oxygen species (ROS) and oxidative stress (OS) seem to play a crucial role. In addition, OS has been implicated in the failure of tendon lesion repair. Platelet-rich plasma (PRP) is rich in growth factors that promote tissue regeneration. This is a promising therapeutic approach in tendon injury. Moreover, growing evidence has been attributed to PRP antioxidant effects that can sustain tissue healing. In this study, the potential antioxidant effects of PRP in tenocytes exposed to oxidative stress were investigated. The results demonstrated that PRP reduces protein and lipid oxidative damage and protects tenocytes from OS-induced cell death. The results also showed that PRP was able to increase nuclear levels of redox-dependent transcription factor Nrf2 and to induce some antioxidant/phase II detoxifying enzymes (superoxide dismutase 2, catalase, heme oxygenase 1, NAD(P)H oxidoreductase quinone-1, glutamate cysteine ligase catalytic subunit and glutathione, S-transferase). Moreover, PRP also increased the enzymatic activity of catalase and glutathione S-transferase. In conclusion, this study suggests that PRP could activate various cellular signaling pathways, including the Nrf2 pathway, for the restoration of tenocyte homeostasis and to promote tendon regeneration and repair following tendon injuries.

Endoplasmic reticulum stress and NF-kB activation in SARS-CoV-2 infected cells and their response to antiviral therapy.

Unfolded protein response (UPR) and endoplasmic reticulum (ER) stress are aspects of SARS-CoV-2-host cell interaction with proposed role in the cytopathic and inflammatory pathogenesis of this viral infection. The role of the NF-kB pathway in these cellular processes remains poorly characterized. When investigated in VERO-E6 cells, SARS-CoV-2 infection was found to markedly stimulate NF-kB protein expression and activity. NF-kB activation occurs early in the infection process (6 hpi) and it is associated with increased MAPK signaling and expression of the UPR inducer IRE-1α. These signal transduction processes characterize the cellular stress response to the virus promoting a pro-inflammatory environment and caspase activation in the host cell. Inhibition of viral replication by the viral protease inhibitor Nelfinavir reverts all these molecular changes also stimulating c-Jun expression, a key component of the JNK/AP-1 pathway with important role in the IRE-1α-mediated transcriptional regulation of stress response genes with anti-inflammatory and cytoprotection function. The present study demonstrates that UPR signaling and its interaction with cellular MAPKs and the NF-kB activity are important aspects of SARS-CoV-2-host cell interaction that deserve further investigation to identify more efficient therapies for this viral infection.

Knowledge, attitudes and practices towards malaria diagnostics among healthcare providers and healthcare-seekers in Kondoa district, Tanzania: a multi-methodological situation analysis.

BACKGROUND: Despite the large-scale rollout of malaria rapid diagnostic tests (RDTs) in Tanzania, many healthcare providers (HCPs) continue using blood film microscopy (BFM) and clinical examination to diagnose malaria, which can increase the risk of mal-diagnosis and over-prescribing of anti-malarials. Patients disregarding negative test results and self-treating exacerbate the problem. This study explored the knowledge, attitudes and practices of HCPs and healthcare-seekers regarding RDTs in comparison to BFM testing. METHODS: A situational analysis was, therefore, conducted in Kondoa District, Dodoma Region, Tanzania. A multi-methodological approach was adopted including (i) a health facility inventory and screening of logbooks from May 2013 to April 2014 with 77,126 patient entries from 33 health facilities; (ii) a survey of 40 HCPs offering malaria services; and iii) a survey of 309 randomly selected household members from the facilities' catchment area. Surveys took place in April and May 2014. RESULTS: Health facility records revealed that out of 77,126 patient entries, 22% (n = 17,235) obtained a malaria diagnosis. Of those, 45% were made with BFM, 33% with RDT and 22% with clinical diagnosis. A higher rate of positive diagnoses was observed with BFM compared with RDT (71% vs 14%). In the HCP survey, 48% preferred using BFM for malaria testing, while 52% preferred RDT. Faced with a negative RDT result for a patient presenting with symptoms typical for malaria, 25% of HCPs stated they would confirm the result with a microscopy test, 70% would advise or perform a clinical diagnosis and 18% would prescribe anti-malarials. Interviews with household members revealed a preference for microscopy testing (58%) over RDT (23%), if presented with malaria symptoms. For participants familiar with both tests, a second opinion was desired in 45% after a negative microscopy result and in 90% after an RDT. CONCLUSIONS: Non-adherence to negative diagnostics by HCPs and patients continues to be a concern. Frequent training and supportive supervision for HCPs diagnosing and treating malaria and non-malaria febrile illnesses is essential to offer quality services that can instil confidence in HCPs and patients alike. The introduction of new diagnostic devices should be paired with context-specific behaviour change interventions targeting healthcare-seekers and healthcare providers.

Melatonin modulates Nrf2 activity to protect porcine pre-pubertal Sertoli cells from the abnormal H2 O2 generation and reductive stress effects of cadmium.

Melatonin (MLT) is a cytoprotective agent holding potential to prevent cadmium (Cd) toxicity and its impact in testicular function and fertility. In this study, we explored such potential in porcine pre-pubertal Sertoli cells (SCs). Cd toxicity resulted in impaired SC viability and function, abnormal cellular H2 O2 generation and efflux, and induction of reductive stress by the upregulation of Nrf2 expression and activity, cystine uptake and glutathione biosynthesis, glutathione-S-transferase P (GSTP) expression, and protein glutathionylation inhibition. Cd toxicity also stimulated the activity of cellular kinases (MAPK-ERK1/2 and Akt) and NFkB transcription factor, and cJun expression was increased. MLT produced a potent cytoprotective effect when co-administered with Cd to SCs; its efficacy and the molecular mechanism behind its cytoprotective function varied according to Cd concentrations. However, a significant restoration of cell viability and function, and of H2 O2 levels, was observed both at 5 and 10 µM Cd. Mechanistically, these effects of MLT were associated with a significant reduction of the Cd-induced activation of Nrf2 and GSTP expression at all Cd concentrations. CAT and MAPK-ERK1/2 activity upregulation was associated with these effects at 5 µM Cd, whereas glutathione biosynthesis and efflux were involved at 10 µM Cd together with an increased expression of the cystine transporter xCT, of cJun and Akt and NFkB activity. MLT protects SCs from Cd toxicity reducing its H2 O2 generation and reductive stress effects. A reduced activity of Nrf2 and the modulation of other molecular players of MLT signaling, provide a mechanistic rational for the cytoprotective effect of this molecule in SCs.

Challenges in cell transplantation for muscular dystrophy.

For decades now, cell transplantation has been considered a possible therapeutic strategy for muscular dystrophy, but failures have largely outnumbered success or at least encouraging outcomes. In this review we will briefly recall the history of cell transplantation, discuss the peculiar features of skeletal muscle, and dystrophic skeletal muscle in particular, that make the procedure complicated and inefficient. As there are many recent and exhaustive reviews on the various myogenic cell types that have been or will be transplanted, we will only briefly describe them and refer the reader to these reviews. Finally, we will discuss possible strategies to overcome the hurdles that prevent biological efficacy and hence clinical success.

Adipose Tissue Plasticity in Response to Pathophysiological Cues: A Connecting Link between Obesity and Its Associated Comorbidities.

Adipose tissue (AT) is a remarkably plastic and active organ with functional pleiotropism and high remodeling capacity. Although the expansion of fat mass, by definition, represents the hallmark of obesity, the dysregulation of the adipose organ emerges as the forefront of the link between adiposity and its associated metabolic and cardiovascular complications. The dysfunctional fat displays distinct biological signatures, which include enlarged fat cells, low-grade inflammation, impaired redox homeostasis, and cellular senescence. While these events are orchestrated in a cell-type, context-dependent and temporal manner, the failure of the adipose precursor cells to form new adipocytes appears to be the main instigator of the adipose dysregulation, which, ultimately, poses a deleterious milieu either by promoting ectopic lipid overspill in non-adipose targets (i.e., lipotoxicity) or by inducing an altered secretion of different adipose-derived hormones (i.e., adipokines and lipokines). This "adipocentric view" extends the previous "expandability hypothesis", which implies a reduced plasticity of the adipose organ at the nexus between unhealthy fat expansion and the development of obesity-associated comorbidities. In this review, we will briefly summarize the potential mechanisms by which adaptive changes to variations of energy balance may impair adipose plasticity and promote fat organ dysfunction. We will also highlight the conundrum with the perturbation of the adipose microenvironment and the development of cardio-metabolic complications by focusing on adipose lipoxidation, inflammation and cellular senescence as a novel triad orchestrating the conspiracy to adipose dysfunction. Finally, we discuss the scientific rationale for proposing adipose organ plasticity as a target to curb/prevent adiposity-linked cardio-metabolic complications.

Natural Cryoprotective and Cytoprotective Agents in Cryopreservation: A Focus on Melatonin.

Cryoprotective and cytoprotective agents (Cytoprotective Agents) are fundamental components of the cryopreservation process. This review presents the essentials of the cryopreservation process by examining its drawbacks and the role of cytoprotective agents in protecting cell physiology. Natural cryoprotective and cytoprotective agents, such as antifreeze proteins, sugars and natural deep eutectic systems, have been compared with synthetic ones, addressing their mechanisms of action and efficacy of protection. The final part of this article focuses melatonin, a hormonal substance with antioxidant properties, and its emerging role as a cytoprotective agent for somatic cells and gametes, including ovarian tissue, spermatozoa and spermatogonial stem cells.

Garcinoic acid prevents ß-amyloid (Aß) deposition in the mouse brain.

Garcinoic acid (GA or δ-T3-13'COOH), is a natural vitamin E metabolite that has preliminarily been identified as a modulator of nuclear receptors involved in ß-amyloid (Aß) metabolism and progression of Alzheimer's disease (AD). In this study, we investigated GA's effects on Aß oligomer formation and deposition. Specifically, we compared them with those of other vitamin E analogs and the soy isoflavone genistein, a natural agonist of peroxisome proliferator-activated receptor γ (PPARγ) that has therapeutic potential for managing AD. GA significantly reduced Aß aggregation and accumulation in mouse cortical astrocytes. Similarly to genistein, GA up-regulated PPARγ expression and apolipoprotein E (ApoE) efflux in these cells with an efficacy that was comparable with that of its metabolic precursor δ-tocotrienol and higher than those of α-tocopherol metabolites. Unlike for genistein and the other vitamin E compounds, the GA-induced restoration of ApoE efflux was not affected by pharmacological inhibition of PPARγ activity, and specific activation of pregnane X receptor (PXR) was observed together with ApoE and multidrug resistance protein 1 (MDR1) membrane transporter up-regulation in both the mouse astrocytes and brain tissue. These effects of GA were associated with reduced Aß deposition in the brain of TgCRND8 mice, a transgenic AD model. In conclusion, GA holds potential for preventing Aß oligomerization and deposition in the brain. The mechanistic aspects of GA's properties appear to be distinct from those of other vitamin E metabolites and of genistein.

TNAP limits TGF-ß-dependent cardiac and skeletal muscle fibrosis by inactivating the SMAD2/3 transcription factors.

Fibrosis is associated with almost all forms of chronic cardiac and skeletal muscle diseases. The accumulation of extracellular matrix impairs the contractility of muscle cells contributing to organ failure. Transforming growth factor ß (TGF-ß) plays a pivotal role in fibrosis, activating pro-fibrotic gene programmes via phosphorylation of SMAD2/3 transcription factors. However, the mechanisms that control de-phosphorylation of SMAD2 and SMAD3 (SMAD2/3) have remained poorly characterized. Here, we show that tissue non-specific alkaline phosphatase (TNAP, also known as ALPL) is highly upregulated in hypertrophic hearts and in dystrophic skeletal muscles, and that the abrogation of TGF-ß signalling in TNAP-positive cells reduces vascular and interstitial fibrosis. We show that TNAP colocalizes and interacts with SMAD2. The TNAP inhibitor MLS-0038949 increases SMAD2/3 phosphorylation, while TNAP overexpression reduces SMAD2/3 phosphorylation and the expression of downstream fibrotic genes. Overall our data demonstrate that TNAP negatively regulates TGF-ß signalling and likely represents a mechanism to limit fibrosis.

Metabolic and functional interplay between gut microbiota and fat-soluble vitamins.

Gut microbiota is a complex ecosystem seen as an extension of human genome. It represents a major metabolic interface of interaction with food components and xenobiotics in the gastrointestinal (GI) environment. In this context, the advent of modern bacterial genome sequencing technology has enabled the identification of dietary nutrients as key determinants of gut microbial ecosystem able to modulate the host-microbiome symbiotic relationship and its effects on human health. This article provides a literature review on functional and molecular interactions between a specific group of lipids and essential nutrients, e.g., fat-soluble vitamins (FSVs), and the gut microbiota. A two-way relationship appears to emerge from the available literature with important effects on human metabolism, nutrition, GI physiology and immune function. First, FSV directly or indirectly modify the microbial composition involving for example immune system-mediated and/or metabolic mechanisms of bacterial growth or inhibition. Second, the gut microbiota influences at different levels the synthesis, metabolism and transport of FSV including their bioactive metabolites that are either introduced with the diet or released in the gut via entero-hepatic circulation. A better understanding of these interactions, and of their impact on intestinal and metabolic homeostasis, will be pivotal to design new and more efficient strategies of disease prevention and therapy, and personalized nutrition.

Weak Microbial Metabolites: a Treasure Trove for Using Biomimicry to Discover and Optimize Drugs.

For decades, traditional drug discovery has used natural product and synthetic chemistry approaches to generate libraries of compounds, with some ending as promising drug candidates. A complementary approach has been to adopt the concept of biomimicry of natural products and metabolites so as to improve multiple drug-like features of the parent molecule. In this effort, promiscuous and weak interactions between ligands and receptors are often ignored in a drug discovery process. In this Emerging Concepts article, we highlight microbial metabolite mimicry, whereby parent metabolites have weak interactions with their receptors that then have led to discrete examples of more potent and effective drug-like molecules. We show specific examples of parent-metabolite mimics with potent effects in vitro and in vivo. Furthermore, we show examples of emerging microbial ligand-receptor interactions and provide a context in which these ligands could be improved as potential drugs. A balanced conceptual advance is provided in which we also acknowledge potential pitfalls-hyperstimulation of finely balanced receptor-ligand interactions could also be detrimental. However, with balance, we provide examples of where this emerging concept needs to be tested. SIGNIFICANCE STATEMENT: Microbial metabolite mimicry is a novel way to expand on the chemical repertoire of future drugs. The emerging concept is now explained using specific examples of the discovery of therapeutic leads from microbial metabolites.

Glutathione S-transferase P influences the Nrf2-dependent response of cellular thiols to seleno-compounds.

Recent findings suggest a functional interaction of the drug resistance enzyme glutathione S-transferase P (GSTP) with the transcription factor Nrf2, a master regulator of the adaptive stress response to cellular electrophiles. The effect of this interaction on the metabolism and redox of cellular thiols was investigated in this study during the exposure to alkylating Se-compounds in murine embryonic fibroblasts (MEFs). GSTP1-1 gene ablation was confirmed to upregulate Nrf2 activity and to increase Cys uptake and the de novo biosynthesis of reduced glutathione (GSH) that was readily released in the extracellular medium together with other cellular thiols. This latter response was associated with a higher expression of the membrane transporter MRP1 and was markedly stimulated by the treatment with alkylating Se-compounds together with protein S-glutathionylation that was observed to be under the influence of  GSTP expression. The response of cellular thiols to Se-compounds was not altered by the transient (SiRNA-induced) or stable inactivation of NRF2 in GSTP competent or hGSTP1 transfected cells, while defects of GSH biosynthesis, efflux, and redox were observed after NRF2 silencing in GSTP-/- MEFs. In conclusion, GSTP is confirmed to functionally interact with Nrf2 and to have a prominent position in the pecking order of factors that control both the Nrf2-dependent and independent response of cellular thiols to alkylating agents.

Co-crystal structure determination and cellular evaluation of 1,4-dihydropyrazolo[4,3-c] [1,2] benzothiazine 5,5-dioxide p38α MAPK inhibitors.

p38α mitogen-activated protein kinase (MAPK) is an attracting pharmacological target in inflammatory diseases and cancer. Searching for new and more efficient p38-MAPK inhibitors, two recently developed pyrazolobenzothiazine-based (COXP4M12 and COXH11) compounds were investigated in this study using a cellular model of p38 activation. This consisted of HT29 human colorectal adenocarcinoma cells exposed to H2O2 or lipopolysaccharide (LPS). Immunoblot data confirmed the inhibitory effect of COXP4M12 and COXH11 on p38 substrate phosphorylation (MAPK-APK2 and ATF2 transcription factor). Compound cytotoxicity was very low and apparent efficacy of these inhibitors was comparable with that of SB203580, a commercially available type I inhibitor of p38. All these compounds also inhibit upstream kinases that promote p38-MAPK phosphorylation and co-activate the stress-activated protein kinase JNK, while ERK1/2 MAPK phosphorylation was unaffected. Compound-target kinase interaction was investigated by means of co-crystallization experiments that provided further structural and molecular insight on the inhibitory mechanism and optimization strategy of this new class of p38-MAPK inhibitors.

Melatonin prevents cadmium-induced bone damage: First evidence on an improved osteogenic/adipogenic differentiation balance of mesenchymal stem cells as underlying mechanism.

Melatonin (MLT) plays a role in preserving bone health, a function that may depend on homeostatic effects on both mature osteoblasts and mesenchymal stem cells (MSCs) of the bone tissue. In this study, these functions of MLT have been investigated in rat bone (femur) and in human adipose MSC (hMSC) during chronic exposure to low-grade cadmium (Cd) toxicity, a serious public health concern. The in vivo findings demonstrate that MLT protects against Cd-induced bone metabolism disruption and accumulation of bone marrow adipocytes, a cue of impaired osteogenic potential of skeletal MSC niches. This latter symptom was recapitulated in hMSCs in which Cd toxicity stimulated adipogenic differentiation. MLT was found to rescue, at least in part, the osteogenic differentiation properties of these cells. This study reports on a new bone cytoprotection function of MLT pertinent to Cd toxicity and its interfering effect on skeletal MSC differentiation properties that is worth investigating for its possible impact on human bone pathophysiology.

Vitamin e-loaded membrane dialyzers reduce hemodialysis inflammaging.

BACKGROUND: Inflammaging is a persistent, low-grade, sterile, nonresolving inflammatory state, associated with the senescence of the immune system. Such condition downregulates both innate and adaptive immune responses during chronic disorders as type II diabetes, cancer and hemodialysis, accounting for their susceptibility to infections, malignancy and resistance to vaccination. Aim of this study was to investigate hemodialysis inflammaging, by evaluating changes of several hemodialysis treatments on indoleamine 2,3-dioxygenase-1 activity and nitric oxide formation. METHODS: We conducted a randomized controlled observational crossover trial. Eighteen hemodialysis patients were treated with 3 different hemodialysis procedures respectively: 1) Low-flux bicarbonate hemodialysis, 2) Low-flux bicarbonate hemodialysis with vitamin E - loaded dialyzers, and 3) Hemodialfitration. The control group consisted of 14 hospital staff healthy volunteers. Blood samples were collected from all 18 hemodialysis patients just after the long interdialytic interval, at the end of each hemodialysis treatment period. RESULTS: Hemodialysis kynurenine and kynurenine/L - tryptophan blood ratio levels were significantly higher, when compared to the control group, indicating an increased indoleamine 2,3-dioxygenase-1 activity in hemodialysis patients. At the end of the low-flux bicarbonate hemodialysis with vitamin E - loaded dialyzers period, L - tryptophan serum levels remained unchanged vs both low-flux bicarbonate hemodialysis and hemodialfitration. Kynurenine levels instead decreased, resulting in a significant reduction of kynurenine/L - tryptophan blood ratio and indoleamine 2,3-dioxygenase-1 activity, when matched to both low-flux bicarbonate hemodialysis and HDF respectively. Serum nitric oxide control group levels, were significantly lower when compared to all hemodialysis patient groups. Interestingly, low-flux bicarbonate hemodialysis with vitamin E - loaded dialyzers nitric oxide serum levels from venous line blood samples taken 60 min after starting the hemodialysis session were significantly lower vs serum taken simultaneously from the arterial blood line. CONCLUSIONS: The treatment with more biocompatible hemodialysis procedure as low-flux bicarbonate hemodialysis with vitamin E - loaded dialyzers, reduced indoleamine 2,3-dioxygenase-1 activity and nitric oxide formation when compared to both low-flux bicarbonate hemodialysis and hemodialfitration. These data suggest that low-flux bicarbonate hemodialysis with vitamin E - loaded dialyzers lowering hemodialysis inflammaging, could be associated to changes of proinflammatory signalling a regulated molecular level. TRIAL REGISTRATION: NCT Number: NCT02981992; Other Study ID Numbers: 20100014090. First submitted: November 26, 2016. First posted: December 5, 2016. Last Update Posted: December 5, 2016.

Long-chain metabolites of vitamin E: Interference with lipotoxicity via lipid droplet associated protein PLIN2.

The long-chain metabolites of vitamin E (LCM) emerge as a new class of regulatory metabolites and have been considered as the active compounds formed during vitamin E metabolism. The bioactivity of the LCM is comparable to the already established role of other fat-soluble vitamins. The biological modes of action of the LCM are far from being unraveled, but first insights pointed to distinct effects and suggested a specific receptor, which in turn lead to the aforementioned hypothesis. Here, a new facet on the interaction of LCM with foam cell formation of THP-1 macrophages is presented. We found reduced levels of mRNA and protein expression of lipid droplet associated protein PLIN2 by α-tocopherol (α-TOH), whereas the LCM and the saturated fatty acid, stearic acid, increased expression levels of PLIN2. In a lipotoxic setup (0-800 µM stearic acid and 0-100 µM α-TOH or 0-5 µM α-13'-COOH) differences in cellular viability were found. A reduced viability was observed for cells under co-treatment of α-TOH and stearic acid, whereas an increased viability for stearic acid incubation in combination with α-13'-COOH was observed. The striking similarity of PLIN2 expression levels and worsened or mitigated lipotoxicity, respectively, revealed a protective effect of PLIN2 on basal stearic acid-induced lipotoxic conditions in PLIN2 knockdown experiments. Based on our results, we conclude that α-13'-COOH protects cells from lipotoxicity, at least partially via PLIN2 regulation. Herewith another facet of LCM functionality was presented and their reputation as regulatory metabolites was further established.