Trail (TNF-related apoptosis-inducing ligand) induces an inflammatory response in human adipocytes

The role of the immune response and inflammatory pathways in TNF-related apoptosis-inducing ligand (TRAIL) resistance in triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer, and the majority of TNBC lacks targeted therapies. Previous studies have shown that TNBC cells are highly sensitive to TNF-related apoptosis-inducing ligand (TRAIL), making it a potentially viable treatment option for TNBC. However, the development of TRAIL resistance limits its potential for clinical use, and the underlying mechanisms are not fully understood. To better understand the mechanism of resistance to TRAIL, we performed RNA sequencing to identify the candidates that are responsible for resistance to TRAIL in two previously established TRAIL-resistant MDA231 and SUM159 cells. This approach led us to identify differentially expressed genes (DEGs) and pathways in TRAIL-resistant MDA231 and SUM159 cells compared to their TRAIL-sensitive counterparts. We showed that several DEGs and pathways were associated with inflammation in TRAIL-resistant cells, including IL-1α and IL6. By downregulating IL-1α and IL6 expression, we showed that TRAIL sensitivity can be significantly restored in TRAIL-resistant cells. Therefore, this study identifies a mechanism by which the inflammation pathway promotes TRAIL resistance, which could be targeted for enhancing TRAIL-based therapies in TNBC cells.

Perivascular spaces in Alzheimer's disease are associated with inflammatory, stress-related, and hypertension biomarkers

Perivascular spaces (PVS) are fluid-filled spaces surrounding the brain vasculature. Literature suggests that PVS may play a significant role in aging and neurological disorders, including Alzheimer's disease (AD). Cortisol, a stress hormone, has been implicated in the development and progression of AD. Hypertension, a common condition in older adults, has been found to be a risk factor for AD. Hypertension may contribute to PVS enlargement, impairing the clearance of waste products from the brain and promoting neuroinflammation. This study aims to understand the potential interactions between PVS, cortisol, hypertension, and inflammation in the context of cognitive impairment. Using MRI scans acquired at 1.5T, PVS were quantified in a cohort of 465 individuals with cognitive impairment. PVS was calculated in the basal ganglia and centrum semiovale using an automated segmentation approach. Levels of cortisol and angiotensin-converting enzyme (ACE) (an indicator of hypertension) were measured from plasma. Inflammatory biomarkers, such as cytokines and matrix metalloproteinases, were analyzed using advanced laboratory techniques. Main effect and interaction analyses were performed to examine the associations between PVS severity, cortisol levels, hypertension, and inflammatory biomarkers. In the centrum semiovale, higher levels of inflammation reduced cortisol associations with PVS volume fraction. For ACE, an inverse association with PVS was seen only when interacting with TNFr2 (a transmembrane receptor of TNF). There was also a significant inverse main effect of TNFr2. In the PVS basal ganglia, a significant positive association was found with TRAIL (a TNF receptor inducing apoptosis). These findings show for the first time the intricate relationships between PVS structure and the levels of stress-related, hypertension, and inflammatory biomarkers. This research could potentially guide future studies regarding the underlying mechanisms of AD pathogenesis and the potential development of novel therapeutic strategies targeting these inflammation factors.

The Role of Cytokines in Cholesterol Accumulation in Cells and Atherosclerosis Progression

Atherosclerosis is the most common cardiovascular disease and is the number one cause of death worldwide. Today, atherosclerosis is a multifactorial chronic inflammatory disease with an autoimmune component, accompanied by the accumulation of cholesterol in the vessel wall and the formation of atherosclerotic plaques, endothelial dysfunction, and chronic inflammation. In the process of accumulation of atherogenic lipids, cells of the immune system, such as monocytes, macrophages, dendritic cells, etc., play an important role, producing and/or activating the production of various cytokines—interferons, interleukins, chemokines. In this review, we have tried to summarize the most important cytokines involved in the processes of atherogenesis.

The Influence of Comorbidities on Chemokine and Cytokine Profile in Obstructive Sleep Apnea Patients: Preliminary Results

INTRODUCTION

Obstructive sleep apnea (OSA) is frequently associated with a chronic inflammatory state and cardiovascular/metabolic complications. The aim of this study was to evaluate the influence of certain comorbidities on a panel of 45 chemokines and cytokines in OSA patients with special regard to their possible association with cardiovascular diseases.

MATERIAL AND METHODS

This cross-sectional study was performed on 61 newly diagnosed OSA patients. For the measurement of the plasma concentration of chemokines and cytokines, the magnetic bead-based multiplex assay for the Luminex^® platform was used.

RESULTS

In the patients with concomitant COPD, there were increased levels of pro-inflammatory cytokines (CCL11, CD-40 ligand) and decreased anti-inflammatory cytokine (IL-10), while in diabetes, there were increased levels of pro-inflammatory cytokines (IL-6, TRIAL). Obesity was associated with increased levels of both pro-inflammatory (IL-13) and anti-inflammatory (IL-1RA) cytokines. Hypertension was associated with increased levels of both pro-inflammatory (CCL3) and anti-inflammatory (IL-10) cytokines. Increased daytime pCO₂, low mean nocturnal SaO₂, and the oxygen desaturation index were associated with increased levels of pro-inflammatory cytokines (CXCL1, PDGF-AB, TNF-α, and IL-15).

CONCLUSIONS

In OSA patients with concomitant diabetes and COPD, elevated levels of certain pro-inflammatory and decreased levels of certain anti-inflammatory cytokines may favor the persistence of a chronic inflammatory state with further consequences. Nocturnal hypoxemia, frequent episodes of desaturation, and increased daytime pCO₂ are factors contributing to the chronic inflammatory state in OSA patients.

Mitochondrial VDAC1: A Potential Therapeutic Target of Inflammation-Related Diseases and Clinical Opportunities

The multifunctional protein, voltage-dependent anion channel 1 (VDAC1), is located on the mitochondrial outer membrane. It is a pivotal protein that maintains mitochondrial function to power cellular bioactivities via energy generation. VDAC1 is involved in regulating energy production, mitochondrial oxidase stress, Ca²⁺ transportation, substance metabolism, apoptosis, mitochondrial autophagy (mitophagy), and many other functions. VDAC1 malfunction is associated with mitochondrial disorders that affect inflammatory responses, resulting in an up-regulation of the body’s defensive response to stress stimulation. Overresponses to inflammation may cause chronic diseases. Mitochondrial DNA (mtDNA) acts as a danger signal that can further trigger native immune system activities after its secretion. VDAC1 mediates the release of mtDNA into the cytoplasm to enhance cytokine levels by activating immune responses. VDAC1 regulates mitochondrial Ca²⁺ transportation, lipid metabolism and mitophagy, which are involved in inflammation-related disease pathogenesis. Many scientists have suggested approaches to deal with inflammation overresponse issues via specific targeting therapies. Due to the broad functionality of VDAC1, it may become a useful target for therapy in inflammation-related diseases. The mechanisms of VDAC1 and its role in inflammation require further exploration. We comprehensively and systematically summarized the role of VDAC1 in the inflammatory response, and hope that our research will lead to novel therapeutic strategies that target VDAC1 in order to treat inflammation-related disorders.

Obesity and Bone Health: A Complex Relationship

Recent scientific evidence has shown an increased risk of fractures in patients with obesity, especially in those with a higher visceral adipose tissue content. This contradicts the old paradigm that obese patients were more protected than those with normal weight. Specifically, in older subjects in whom there is a redistribution of fat from subcutaneous adipose tissue to visceral adipose tissue and an infiltration of other tissues such as muscle with the consequent sarcopenia, obesity can accentuate the changes characteristic of this age group that predisposes to a greater risk of falls and fractures. Other factors that determine a greater risk in older subjects with obesity are chronic proinflammatory status, altered adipokine secretion, vitamin D deficiency, insulin resistance and reduced mobility. On the other hand, diagnostic tests may be influenced by obesity and its comorbidities as well as by body composition, and risk scales may underestimate the risk of fractures in these patients. Weight loss with physical activity programs and cessation of high-fat diets may reduce the risk. Finally, more research is needed on the efficacy of anti-osteoporotic treatments in obese patients.

Repositioning the Role of Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL) on the TRAIL to the Development of Diabetes Mellitus: An Update of Experimental and Clinical Evidence

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a member of the TNF protein superfamily, represents a multifaceted cytokine with unique biological features including both proapoptotic and pro-survival effects in different cell types depending on receptor interactions and local stimuli. Beyond its extensively studied anti-tumor and immunomodulatory properties, a growing body of experimental and clinical evidence over the past two decades suggests a protective role of TRAIL in the development of type 1 (T1DM) and type 2 (T2DM) diabetes mellitus. This evidence can be briefly summarized by the following observations: (i) acceleration and exacerbation of T1DM and T2DM by TRAIL blockade or genetic deficiency in animal models, (ii) prevention and amelioration of T1DM and T2DM with recombinant TRAIL treatment or systemic TRAIL gene delivery in animal models, (iii) significantly reduced circulating soluble TRAIL levels in patients with T1DM and T2DM both at disease onset and in more advanced stages of diabetes-related complications such as cardiovascular disease and diabetic nephropathy, (iv) increase of serum TRAIL levels in diabetic patients after initiation of antidiabetic treatment and metabolic improvement. To explore the underlying mechanisms and provide mechanistic links between TRAIL and diabetes, a number of animal and in vitro studies have reported direct effects of TRAIL on several tissues involved in diabetes pathophysiology such as pancreatic islets, skeletal muscle, adipose tissue, liver, kidney, and immune and vascular cells. Residual controversy remains regarding the effects of TRAIL on adipose tissue homeostasis. Although the existing evidence is encouraging and paves the way for investigating TRAIL-related interventions in diabetic patients with cardiometabolic abnormalities, caution is warranted in the extrapolation of animal and in vitro data to the clinical setting, and further research in humans is imperative in order to uncover all aspects of the TRAIL-diabetes relationship and delineate its therapeutic implications in metabolic disease.

Homer1 promotes the conversion of A1 astrocytes to A2 astrocytes and improves the recovery of transgenic mice after intracerebral hemorrhage

Background

Inflammation induced by intracerebral hemorrhage (ICH) is one of the main causes of the high mortality and poor prognosis of patients with ICH. A1 astrocytes are closely associated with neuroinflammation and neurotoxicity, whereas A2 astrocytes are neuroprotective. Homer scaffolding protein 1 (Homer1) plays a protective role in ischemic encephalopathy and neurodegenerative diseases. However, the role of Homer1 in ICH-induced inflammation and the effect of Homer1 on the phenotypic conversion of astrocytes remain unknown.

Methods

Femoral artery autologous blood from C57BL/6 mice was used to create an ICH model. We use the A1 phenotype marker C3 and A2 phenotype marker S100A10 to detect astrocyte conversion after ICH. Homer1 overexpression/knock-down mice were constructed by adeno-associated virus (AAV) infection to explore the role of Homer1 and its mechanism of action after ICH. Finally, Homer1 protein and selumetinib were injected into in situ hemorrhage sites in the brains of Homer1^flox/flox/Nestin-Cre^+/− mice to study the efficacy of Homer1 in the treatment of ICH by using a mouse cytokine array to explore the potential mechanism.

Results

The expression of Homer1 peaked on the third day after ICH and colocalized with astrocytes. Homer1 promotes A1 phenotypic conversion in astrocytes in vivo and in vitro. Overexpression of Homer1 inhibits the activation of MAPK signaling, whereas Homer1 knock-down increases the expression of pathway-related proteins. The Homer1 protein and selumetinib, a non-ATP competitive MEK1/2 inhibitor, improved the outcome in ICH in Homer1^flox/flox/Nestin-Cre^+/− mice. The efficacy of Homer1 in the treatment of ICH is associated with reduced expression of the inflammatory factor TNFSF10 and increased expression of the anti-inflammatory factors activin A, persephin, and TWEAK.

Conclusions

Homer1 plays an important role in inhibiting inflammation after ICH by suppressing the A1 phenotype conversion in astrocytes. In situ injection of Homer1 protein may be a novel and effective method for the treatment of inflammation after ICH.

Estrogen Receptor α Signaling in Osteoblasts is Required for Mechanotransduction in Bone Fracture Healing

Biomechanical stimulation by whole-body low-magnitude high-frequency vibration (LMHFV) has demonstrated to provoke anabolic effects on bone metabolism in both non-osteoporotic and osteoporotic animals and humans. However, preclinical studies reported that vibration improved fracture healing and bone formation in osteoporotic, ovariectomized (OVX) mice representing an estrogen-deficient hormonal status, but impaired bone regeneration in skeletally healthy non-OVX mice. These effects were abolished in general estrogen receptor α (ERα)-knockout (KO) mice. However, it remains to be elucidated which cell types in the fracture callus are targeted by LMHFV during bone healing. To answer this question, we generated osteoblast lineage-specific ERα-KO mice that were subjected to ovariectomy, femur osteotomy and subsequent vibration. We found that the ERα specifically on osteoblastic lineage cells facilitated the vibration-induced effects on fracture healing, because in osteoblast lineage-specific ERα-KO (ERα^{fl/fl; Runx2Cre}) mice the negative effects in non-OVX mice were abolished, whereas the positive effects of vibration in OVX mice were reversed. To gain greater mechanistic insights, the influence of vibration on murine and human osteogenic cells was investigated in vitro by whole genome array analysis and qPCR. The results suggested that particularly canonical WNT and Cox2/PGE₂ signaling is involved in the mechanotransduction of LMHFV under estrogen-deficient conditions. In conclusion, our study demonstrates a critical role of the osteoblast lineage-specific ERα in LMHFV-induced effects on fracture healing and provides further insights into the molecular mechanism behind these effects.

Type 2 Innate Lymphoid Cells: Protectors in Type 2 Diabetes

Type 2 innate lymphoid cells (ILC2) are the innate counterparts of Th2 cells and are critically involved in the maintenance of homeostasis in a variety of tissues. Instead of expressing specific antigen receptors, ILC2s respond to external stimuli such as alarmins released from damage. These cells help control the delicate balance of inflammation in adipose tissue, which is a determinant of metabolic outcome. ILC2s play a key role in the pathogenesis of type 2 diabetes mellitus (T2DM) through their protective effects on tissue homeostasis. A variety of crosstalk takes place between resident adipose cells and ILC2s, with each interaction playing a key role in controlling this balance. ILC2 effector function is associated with increased browning of adipose tissue and an anti-inflammatory immune profile. Trafficking and maintenance of ILC2 populations are critical for tissue homeostasis. The metabolic environment and energy source significantly affect the number and function of ILC2s in addition to affecting their interactions with resident cell types. How ILC2s react to changes in the metabolic environment is a clear determinant of the severity of disease. Treating sources of metabolic instability via critical immune cells provides a clear avenue for modulation of systemic homeostasis and new treatments of T2DM.

Inflammatory profiles in Chilean Mapuche and non-Mapuche women with gallstones at risk of developing gallbladder cancer

Chile has high incidence rates of gallbladder cancer globally, particularly among Amerindian women, who also have a high prevalence of gallstones. We examined differences in inflammatory biomarkers between Mapuche and non-Mapuche women from the Chile Biliary Longitudinal Study, a cohort of women with ultrasound-detected gallstones. We randomly selected 200 Mapuche women frequency matched to non-Mapuche women on age and statin use Inflammatory biomarkers were analyzed using a multiplex assay and linear regression to assess associations of a priori markers (CCL20, CXCL10, IL-6, and IL-8) with ethnicity. Novel biomarkers were analyzed using exploratory factor analysis (EFA) and sufficient dimension reduction (SDR) to identify correlated marker groups, followed by linear regression to examine their association with ethnicity. The mean values of IL-8 were higher in Mapuche than non-Mapuche women (P = 0.04), while CCL20, CXCL10, and IL-6 did not differ significantly by ethnicity. EFA revealed two marker groups associated with ethnicity (P = 0.03 and P < 0.001). SDR analysis confirmed correlation between the biomarkers and ethnicity. We found higher IL-8 levels among Mapuche than non-Mapuche women. Novel inflammatory biomarkers were correlated with ethnicity and should be studied further for their role in gallbladder disease. These findings may elucidate underlying ethnic disparities in gallstones and carcinogenesis among Amerindians.

The Role of Inflammatory Cytokines as Intermediates in the Pathway from Increased Adiposity to Disease

OBJECTIVE

This study aimed to investigate the role of cytokines as intermediates in the pathway from increased adiposity to disease.

METHODS

BMI and circulating levels of up to 41 cytokines were measured in individuals from three Finnish cohort studies (n = 8,293). Mendelian randomization (MR) was used to assess the impact of BMI on circulating cytokines and the impact of BMI-driven cytokines on risk of obesity-related diseases.

RESULTS

Observationally, BMI was associated with 19 cytokines. For every SD increase in BMI, causal effect estimates were strongest for hepatocyte growth factor, monocyte chemotactic protein-1 (MCP-1), and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and were as ratios of geometric means 1.13 (95% CI: 1.08-1.19), 1.08 (95% CI: 1.04-1.14), and 1.13 (95% CI: 1.04-1.21), respectively. TRAIL was associated with a small increase in the odds of coronary artery disease (odds ratio: 1.03; 95% CI: 1.00-1.06). There was inconsistent evidence for a protective role of MCP-1 against inflammatory bowel diseases.

CONCLUSIONS

Observational and MR estimates of the effect of BMI on cytokine levels were generally concordant. There was little evidence for an effect of raised levels of BMI-driven cytokines on disease. These findings illustrate the challenges of MR when applied in the context of molecular mediation.

A TRAIL-TL1A Paracrine Network Involving Adipocytes, Macrophages, and Lymphocytes Induces Adipose Tissue Dysfunction Downstream of E2F1 in Human Obesity

Elevated expression of E2F1 in adipocyte fraction of human visceral adipose tissue (hVAT) associates with a poor cardiometabolic profile. We hypothesized that beyond directly activating autophagy and MAP3K5 (ASK)-MAP kinase signaling, E2F1 governs a distinct transcriptome that contributes to adipose tissue and metabolic dysfunction in obesity. We performed RNA sequencing of hVAT samples from age-, sex-, and BMI-matched patients, all obese, whose visceral E2F1 protein expression was either high (E2F1^high) or low (E2F1^low). Tumor necrosis factor superfamily (TNFSF) members, including TRAIL (TNFSF10), TL1A (TNFSF15), and their receptors, were enriched in E2F1^high While TRAIL was equally expressed in adipocytes and stromal vascular fraction (SVF), TL1A was mainly expressed in SVF, and TRAIL-induced TL1A was attributed to CD4⁺ and CD8⁺ subclasses of hVAT T cells. In human adipocytes, TL1A enhanced basal and impaired insulin-inhibitable lipolysis and altered adipokine secretion, and in human macrophages it induced foam cell biogenesis and M1 polarization. Two independent human cohorts confirmed associations between TL1A and TRAIL expression in hVAT and higher leptin and IL6 serum concentrations, diabetes status, and hVAT-macrophage lipid content. Jointly, we propose an intra-adipose tissue E2F1-associated TNFSF paracrine loop engaging lymphocytes, macrophages, and adipocytes, ultimately contributing to adipose tissue dysfunction in obesity.

The immune system on the TRAIL of Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia, characterized by progressive degeneration and loss of neurons in specific regions of the central nervous system. Chronic activation of the immune cells resident in the brain, peripheral immune cell trafficking across the blood-brain barrier, and release of inflammatory and neurotoxic factors, appear critical contributors of the neuroinflammatory response that drives the progression of neurodegenerative processes in AD. As the neuro-immune network is impaired in course of AD, this review is aimed to point out the essential supportive role of innate and adaptive immune response either in normal brain as well as in brain recovery from injury. Since a fine-tuning of the immune response appears crucial to ensure proper nervous system functioning, we focused on the role of the TNF superfamily member, TNF-related apoptosis-inducing ligand (TRAIL), which modulates both the innate and adaptive immune response in the pathogenesis of several immunological disorders and, in particular, in AD-related neuroinflammation. We here summarized mounting evidence of potential involvement of TRAIL signaling in AD pathogenesis, with the aim to provide clearer insights about potential novel therapeutic approaches in AD.

The role of caspase-8 in the tumor microenvironment of ovarian cancer

Caspase-8 is an aspartate-specific cysteine protease, which is best known for its apoptotic functions. Caspase-8 is placed at central nodes of multiple signal pathways, regulating not only the cell cycle but also the invasive and metastatic cell behavior, the immune cell homeostasis and cytokine production, which are the two major components of the tumor microenvironment (TME). Ovarian cancer often has dysregulated caspase-8 expression, leading to imbalance between its apoptotic and non-apoptotic functions within the tumor and the surrounding milieu. The downregulation of caspase-8 in ovarian cancer seems to be linked to high aggressiveness with chronic inflammation, immunoediting, and immune resistance. Caspase-8 plays therefore an essential role not only in the primary tumor cells but also in the TME by regulating the immune response, B and T lymphocyte activation, and macrophage differentiation and polarization. The switch between M1 and M2 macrophages is possibly associated with changes in the caspase-8 expression. In this review, we are discussing the non-apoptotic functions of caspase-8, highlighting this protein as a modulator of the immune response and the cytokine composition in the TME. Considering the low survival rate among ovarian cancer patients, it is urgently necessary to develop new therapeutic strategies to optimize the response to the standard treatment. The TME is highly heterogenous and provides a variety of opportunities for new drug targets. Given the variety of roles of caspase-8 in the TME, we should focus on this protein in the development of new therapeutic strategies against the TME of ovarian cancer.

Muscle-derived TRAIL negatively regulates myogenic differentiation

TNF-related apoptosis-inducing ligand (TRAIL) is known to induce apoptosis in cancer cells, although non-apoptotic functions have also been reported for this cytokine in various cell types. TRAIL and its receptor TRAIL-R2 are expressed in skeletal muscles, but a potential role of muscle-derived TRAIL in myogenesis has not been explored. Here we report that TRAIL is an autocrine regulator of myogenic differentiation. Knockdown of TRAIL or TRAIL-R2 enhanced C2C12 myoblast differentiation, and recombinant TRAIL inhibited expression of the cell cycle inhibitor p21, accompanied by suppression of myoblasts from exiting the cell cycle, a requisite step in the myogenic differentiation process. Blocking cell cycle progression restored differentiation from inhibition by recombinant TRAIL, supporting the notion that TRAIL exerts its effect in myogenesis through modulating cell cycle exit. We also found that TRAIL knockdown led to enhanced muscle regeneration in mice upon injury, recapitulating the in vitro observation. Additionally, inhibition of ERK activation reversed the negative effect of recombinant TRAIL on p21 expression and myoblast differentiation, suggesting that ERK signaling may be a mediator of TRAIL's function to suppress cell cycle withdrawal and inhibit differentiation. Taken together, our findings uncover a muscle cell-autonomous non-apoptotic function of TRAIL in skeletal myogenesis.

Involvement of NF-κB1 and the Non-Canonical NF-κB Signaling Pathway in the Pathogenesis of Acute Kidney Injury in Shiga-Toxin-2-Induced Hemolytic-Uremic Syndrome in Mice

The hemolytic-uremic syndrome (HUS) is a thrombotic microangiopathy which can occur as a severe systemic complication after an infection with Shiga-toxin-(Stx)-producing Escherichia coli (STEC). Elevated levels of proinflammatory cytokines associated with the classical NF-κB signaling pathway were detected in the urine of HUS patients. Thus, we hypothesize that the immune response of the infected organism triggered by Stx can affect the kidneys and contributes to acute kidney injury. Hitherto the role of the classical and non-canonical NF-κB signaling pathway in HUS has not been evaluated systematically in vivo. We aimed to investigate in a murine model of Shiga toxin-induced HUS-like disease, whether one or both pathways are involved in the renal pathology in HUS. In kidneys of mice subjected to Stx or sham-treated mice, protein or gene expression analyses were performed to assess the 1) expression of receptors activating the classical and non-canonical pathway, such as Fn14 and CD40 2) levels of NF-κB1/RelA and NF-κB2/RelB including its upstream signaling proteins and 3) expression of cytokines as target molecules of both pathways. In line with a higher expression of Fn14 and CD40, we detected an enhanced translocation of NF-κB1 and RelA as well as NF-κB2 and RelB into the nucleus accompanied by an increased gene expression of the NF-κB1-target cytokines Ccl20, Cxcl2, Ccl2, Cxcl1, IL-6, TNF-α, Cxcl10 and Ccl5, indicating an activation of the classical and non-canonical NF-κB pathway. Thereby, we provide, for the first time, in vivo evidence for an involvement of both NF-κB signaling pathways in renal pathophysiology of STEC-HUS.

Lipid metabolism adaptations are reduced in human compared to murine Schwann cells following injury

Mammals differ in their regeneration potential after traumatic injury, which might be caused by species-specific regeneration programs. Here, we compared murine and human Schwann cell (SC) response to injury and developed an ex vivo injury model employing surgery-derived human sural nerves. Transcriptomic and lipid metabolism analysis of murine SCs following injury of sural nerves revealed down-regulation of lipogenic genes and regulator of lipid metabolism, including Pparg (peroxisome proliferator-activated receptor gamma) and S1P (sphingosine-1-phosphate). Human SCs failed to induce similar adaptations following ex vivo nerve injury. Pharmacological PPARg and S1P stimulation in mice resulted in up-regulation of lipid gene expression, suggesting a role in SCs switching towards a myelinating state. Altogether, our results suggest that murine SC switching towards a repair state is accompanied by transcriptome and lipidome adaptations, which are reduced in humans.

Impaired circulating CD56dim NK cells are associated with decompensation of HBV-related cirrhosis

NK cells play an important role in immune regulation and defense of infection, but their characteristics in patients with decompensated cirrhosis and their relationship with liver function remain unclear. We studied the functional properties of NK cells (including CD56^dim NK and CD56^bright NK cells) in patients with HBV-related decompensated liver cirrhosis (HBV-DLC) and analyzed their relationship with decompensation of liver function. Thirty patients with HBV-DLC and 25 patients with HBV-related compensated liver cirrhosis (HBV-CLC) were recruited in this study. Twenty five age- and sex-matched healthy individuals were recruited as healthy controls (HCs). The phenotypical and functional characteristics of NK cell subsets were detected by flow cytometry, and the correlation between NK cells and decompensation of liver function was analyzed. The frequency of circulating CD56^bright NK cells was significantly increased while circulating CD56^dim NK cells was significantly decreased in HBV-DLC patients as compared with HCs and HBV-CLC patients. Peripheral activated-CD56^bright NK cells from HBV-DLC patients might express lower levels of inhibitory receptor CD158b1/2 and higher levels of activating receptor NKG2D and their expression of perforin and granzyme A/B also increased significantly compared with HCs, suggesting a high immune activation status of peripheral CD56^bright NK cells in HBV-DLC patients. In HBV-DLC patients, the expression of CD107a and perforin in circulating CD56^dim NK cells was positively correlated with cytolytic capacity while CD107a and perforin expression in circulating CD56^dim NK cells were significantly decreased, suggesting an impaired cytolytic capacity of circulating CD56^dim NK cells. Besides, we found that the perforin expression of circulating CD56^dim NK cells correlated negatively with child-pugh classification in HBV-DLC patients. The functional properties of circulating NK cell subsets in HBV-DLC patients have changed significantly, especially of CD56^dim NK cells which closely related to decompensation of liver function. These findings may help provide new perspectives and theoretical basis for the treatment of patients with HBV-DLC.

Hydroxytyrosol Modulates Adipocyte Gene and miRNA Expression Under Inflammatory Condition

Chronic inflammation of the adipose tissue (AT) is a major contributor to obesity-associated cardiometabolic complications. The olive oil polyphenol hydroxytyrosol (HT) contributes to Mediterranean diet cardiometabolic benefits through mechanisms still partially unknown. We investigated HT (1 and 10 μmol/L) effects on gene expression (mRNA and microRNA) related to inflammation induced by 10 ng/mL tumor necrosis factor (TNF)-α in human Simpson–Golabi–Behmel Syndrome (SGBS) adipocytes. At real-time PCR, HT significantly inhibited TNF-α-induced mRNA levels, of monocyte chemoattractant protein-1, C-X-C Motif Ligand-10, interleukin (IL)-1β, IL-6, vascular endothelial growth factor, plasminogen activator inhibitor-1, cyclooxygenase-2, macrophage colony-stimulating factor, matrix metalloproteinase-2, Cu/Zn superoxide dismutase-1, and glutathione peroxidase, as well as surface expression of intercellular adhesion molecule-1, and reverted the TNF-α-mediated inhibition of endothelial nitric oxide synthase, peroxisome proliferator-activated receptor coactivator-1α, and glucose transporter-4. We found similar effects in adipocytes stimulated by macrophage-conditioned media. Accordingly, HT significantly counteracted miR-155-5p, miR-34a-5p, and let-7c-5p expression in both cells and exosomes, and prevented NF-κB activation and production of reactive oxygen species. HT can therefore modulate adipocyte gene expression profile through mechanisms involving a reduction of oxidative stress and NF-κB inhibition. By such mechanisms, HT may blunt macrophage recruitment and improve AT inflammation, preventing the deregulation of pathways involved in obesity-related diseases.

Beyond adiponectin and leptin: adipose tissue-derived mediators of inter-organ communication

The breakthrough discoveries of leptin and adiponectin more than two decades ago led to a widespread recognition of adipose tissue as an endocrine organ. Many more adipose tissue-secreted signaling mediators (adipokines) have been identified since then, and much has been learned about how adipose tissue communicates with other organs of the body to maintain systemic homeostasis. Beyond proteins, additional factors, such as lipids, metabolites, noncoding RNAs, and extracellular vesicles (EVs), released by adipose tissue participate in this process. Here, we review the diverse signaling mediators and mechanisms adipose tissue utilizes to relay information to other organs. We discuss recently identified adipokines (proteins, lipids, and metabolites) and briefly outline the contributions of noncoding RNAs and EVs to the ever-increasing complexities of adipose tissue inter-organ communication. We conclude by reflecting on central aspects of adipokine biology, namely, the contribution of distinct adipose tissue depots and cell types to adipokine secretion, the phenomenon of adipokine resistance, and the capacity of adipose tissue to act both as a source and sink of signaling mediators.

MicroRNA-181a exerts anti-inflammatory effects via inhibition of the ERK pathway in mice with intervertebral disc degeneration

Enzymatic decomposition of extracellular matrix and possibly local inflammation may cause intervertebral disc degeneration (IDD). MicroRNAs have been reported to correlate with the development of IDD. In this experiment, we aim at finding out the role of miR-181a in the inflammation of IDD and the underlying mechanism. The targeting relationship between miR-181a and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was verified. Following the establishment of IDD mouse models, disc height index (DHI) and the change of DHI (%DHI) were measured. The functional role of miR-181a in IDD was determined using ectopic expression and depletion and reporter assay experiments. Expression of miR-181a, TRAIL, extracellular signal-regulated kinase (ERK) pathway-related genes and inflammatory factors was evaluated. Also, the expression of collagen I and collagen II was observed. miR-181a directly targeted TRAIL. IDD mice exhibited significant degeneration of the intervertebral disc. miR-181a was downregulated while TRAIL was upregulated in mice with IDD. miR-181a upregulation and the ERK pathway inhibition could reduce expression of TRAIL, ERK pathway-related genes, inflammatory factors, and collagen I, but promote collagen II expression. Our results reveal that upregulation of miR-181a protects against inflammatory response by inactivating the ERK pathway via suppression of TRAIL in IDD mice. These results point to miR-181a as a potential therapeutic target for the clinical management of IDD.

Mechanisms Involved in Childhood Obesity-Related Bone Fragility

Childhood obesity is one of the major health problems in western countries. The excessive accumulation of adipose tissue causes inflammation, oxidative stress, apoptosis, and mitochondrial dysfunctions. Thus, obesity leads to the development of severe co-morbidities including type 2 diabetes mellitus, liver steatosis, cardiovascular, and neurodegenerative diseases which can develop early in life. Furthermore, obese children have low bone mineral density and a greater risk of osteoporosis and fractures. The knowledge about the interplay bone tissue and between adipose is still growing, although recent findings suggest that adipose tissue activity on bone can be fat-depot specific. Obesity is associated to a low-grade inflammation that alters the expression of adiponectin, leptin, IL-6, Monocyte Chemotactic Protein 1 (MCP1), TRAIL, LIGHT/TNFSF14, OPG, and TNFα. These molecules can affect bone metabolism, thus resulting in osteoporosis. The purpose of this review was to deepen the cellular mechanisms by which obesity may facilitate osteoporosis and bone fractures.

Visceral white adipose tissue and serum proteomic alternations in metabolically healthy obese patients undergoing bariatric surgery

Metabolically healthy obesity is characterized as a comorbidity-free obesity status, however the exact pathogenetic mechanisms implicated in its transition to unhealthy obesity have not yet been unveiled. Our aim was to investigate the effect of metabolic health on the proteomic profile both in serum and visceral fat of morbidly obese subjects. 28 patients undergoing bariatric surgery were prospectively enrolled. They were divided into two groups: metabolically healthy (MHO, n = 18) and unhealthy (MUO, n = 10) obese patients. 30 biomarkers were measured in serum and visceral adipose tissue with the use of targeted proteomic analysis (Luminex assays). TNF weak inducer of apoptosis (TWEAK) (p = 0.043), TNF related apoptosis inducing ligand (TRAIL) (p = 0.037), Growth differentiation factor-15 (GDF-15) (p = 0.04), Resistin (RETN) (p = 0.047), Matrix metalloproteinase-9 (MMP-9) (p = 0.011) and C-terminal telopeptide (ICTP) (p = 0.022) were up-regulated in the MUO group in the visceral white adipose tissue. Moreover, C-C motif ligand-3 (CCL-3) (p = 0.056), Interleukin-20 (IL-20) (p = 0.04), Prokineticin-1 (PROK-1) (p = 0.028) and TWEAK (p = 0.016) were found to be suppressed in the serum of MHO group. Significant correlations between serum and adipose tissue levels of certain cytokines were also observed, while 16 biomarkers were associated with BMI. Our results indicate metabolic health substantially attenuates the expression of TWEAK, TRAIL, GDF-15, RETN, MMP-9 and ICTP expression locally, in the visceral white adipose tissue, and the expression of CCL-3, IL-20, PROK-1 and TWEAK in the peripheral blood. Intriguingly, different cytokines -except for TWEAK- are up-regulated in each site, suggesting that obesity is not a homogenous but a multi-dimensional disease.

C5aR1 interacts with TLR2 in osteoblasts and stimulates the osteoclast-inducing chemokine CXCL10

The anaphylatoxin C5a is generated upon activation of the complement system, a crucial arm of innate immunity. C5a mediates proinflammatory actions via the C5a receptor C5aR1 and thereby promotes host defence, but also modulates tissue homeostasis. There is evidence that the C5a/C5aR1 axis is critically involved both in physiological bone turnover and in inflammatory conditions affecting bone, including osteoarthritis, periodontitis, and bone fractures. C5a induces the migration and secretion of proinflammatory cytokines of osteoblasts. However, the underlying mechanisms remain elusive. Therefore, in this study we aimed to determine C5a‐mediated downstream signalling in osteoblasts. Using a whole‐genome microarray approach, we demonstrate that C5a activates mitogen‐activated protein kinases (MAPKs) and regulates the expression of genes involved in pathways related to insulin, transforming growth factor‐β and the activator protein‐1 transcription factor. Interestingly, using coimmunoprecipitation, we found an interaction between C5aR1 and Toll‐like receptor 2 (TLR2) in osteoblasts. The C5aR1‐ and TLR2‐signalling pathways converge on the activation of p38 MAPK and the generation of C‐X‐C motif chemokine 10, which functions, among others, as an osteoclastogenic factor. In conclusion, C5a‐stimulated osteoblasts might modulate osteoclast activity and contribute to immunomodulation in inflammatory bone disorders.

USP6 Confers Sensitivity to IFN-Mediated Apoptosis through Modulation of TRAIL Signaling in Ewing Sarcoma

Ewing sarcoma is the second most common sarcoma of the bone, afflicting predominantly the pediatric population. Although patients with localized disease exhibit favorable survival rates, patients with metastatic disease suffer a dismal 5-year rate of approximately 25%. Thus, there is a great need to develop treatments to combat the disseminated disease. Ubiquitin-specific protease 6 (USP6/TRE17) has been implicated as the key etiologic factor in several benign mesenchymal tumors, including nodular fasciitis and aneurysmal bone cyst (ABC). However, the role of USP6 in the biology of malignant entities remains unexplored. Previously, it was observed that USP6 is sufficient to drive formation of tumors mimicking ABC and nodular fasciitis, and that it functions through JAK1/STAT3 signaling. However, in the context of Ewing sarcoma, USP6 does not enhance the transformation, but rather triggers an IFN response signature, both in cultured Ewing sarcoma cells in vitro and in clinical specimens in vivo. Not only does USP6 independently induce activation of the IFN signaling mediators, JAK1 and STAT1, but it also renders Ewing sarcoma cells exquisitely responsive to exogenous IFNs, potentiating activation of STAT1 and STAT3. Furthermore, IFNβ (a type I IFN) induces apoptosis specifically in USP6-positive but not USP6-negative Ewing sarcoma cells. Finally, apoptosis is mediated through the proapoptotic ligand TRAIL, which is synergistically induced by type I IFN and USP6. IMPLICATIONS: These findings provide the first insights into USP6 functions in a clinically relevant malignant entity, and raise the possibility of using IFN for targeting USP6-positive Ewing sarcoma.