Implication of REDD1 in the activation of inflammatory pathways

Decreasing REDD1 expression protects against high glucose-induced apoptosis, oxidative stress and inflammatory injury in podocytes through regulation of the AKT/GSK-3β/Nrf2 pathway

OBJECTIVE

Our goal in this work was to investigate the possible role and mechanism of regulated in development and DNA damage response 1 (REDD1) in mediating high glucose (HG)-induced podocyte injury in vitro.

MATERIALS AND METHODS

Mouse podocytes were stimulated with HG to establish HG injury model. Protein expression was examined by Western blotting. Cell viability was measured by cell counting kit-8 assay. Cell apoptosis was assessed by annexin V-FITC/propidium iodide and TUNEL apoptotic assays. Levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GPx) were quantified by commercial kits. Concentrations of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β were measured by ELISA.

RESULTS

A marked increase in REDD1 expression was observed in podocytes stimulated with HG. Reduced REDD1 expression strikingly restrained HG-induced increases in apoptosis, oxidative stress, and inflammation response in cultured podocytes. Decreasing REDD1 expression enhanced nuclear factor erythroid 2-related factor 2 (Nrf2) activation in HG-exposed podocytes via regulation of the AKT/glycogen synthase kinase-3 beta (GSK-3β) pathway. Inhibition of AKT or reactivation of GSK-3β prominently abolished Nrf2 activation induced by decreasing REDD1 expression. Pharmacological repression of Nrf2 markedly reversed the protective effects of decreasing REDD1 expression in HG-injured podocytes.

CONCLUSION

Our data demonstrate that decreasing REDD1 expression protects cultured podocytes from HG-induced injuries by potentiating Nrf2 signaling through regulation of the AKT/GSK-3β pathway. Our work underscores the potential role of REDD1-mediated podocyte injury during the development of diabetic kidney disease.

The stress-responsive protein REDD1 and its pathophysiological functions

Regulated in development and DNA damage-response 1 (REDD1) is a stress-induced protein that controls various cellular functions, including metabolism, oxidative stress, autophagy, and cell fate, and contributes to the pathogenesis of metabolic and inflammatory disorders, neurodegeneration, and cancer. REDD1 usually exerts deleterious effects, including tumorigenesis, metabolic inflammation, neurodegeneration, and muscle dystrophy; however, it also exhibits protective functions by regulating multiple intrinsic cell activities through either an mTORC1-dependent or -independent mechanism. REDD1 typically regulates mTORC1 signaling, NF-κB activation, and cellular pro-oxidant or antioxidant activity by interacting with 14-3-3 proteins, IκBα, and thioredoxin-interacting protein or 75 kDa glucose-regulated protein, respectively. The diverse functions of REDD1 depend on cell type, cellular context, interaction partners, and cellular localization (e.g., mitochondria, endomembrane, or cytosol). Therefore, comprehensively understanding the molecular mechanisms and biological roles of REDD1 under pathophysiological conditions is of utmost importance. In this review, based on the published literature, we highlight and discuss the molecular mechanisms underlying the REDD1 expression and its actions, biological functions, and pathophysiological roles.

REDD1-dependent GSK3β dephosphorylation promotes NF-κB activation and macrophage infiltration in the retina of diabetic mice

Increasing evidence supports a role for inflammation in the early development and progression of retinal complications caused by diabetes. We recently demonstrated that the stress response protein regulated in development and DNA damage response 1 (REDD1) promotes diabetes-induced retinal inflammation by sustaining canonical activation of nuclear transcription factor, NF-κB. The studies here were designed to identify signaling events whereby REDD1 promotes NF-κB activation in the retina of diabetic mice. We observed increased REDD1 expression in the retina of mice after 16 weeks of streptozotocin (STZ)-induced diabetes and found that REDD1 was essential for diabetes to suppress inhibitory phosphorylation of glycogen synthase kinase 3β (GSK3β) at S9. In human retinal MIO-M1 Müller cell cultures, REDD1 deletion prevented dephosphorylation of GSK3β and increased NF-κB activation in response to hyperglycemic conditions. Expression of a constitutively active GSK3β variant restored NF-κB activation in cells deficient for REDD1. In cells exposed to hyperglycemic conditions, GSK3β knockdown inhibited NF-κB activation and proinflammatory cytokine expression by preventing inhibitor of κB kinase complex autophosphorylation and inhibitor of κB degradation. In both the retina of STZ-diabetic mice and in Müller cells exposed to hyperglycemic conditions, GSK3 inhibition reduced NF-κB activity and prevented an increase in proinflammatory cytokine expression. In contrast with STZ-diabetic mice receiving a vehicle control, macrophage infiltration was not observed in the retina of STZ-diabetic mice treated with GSK3 inhibitor. Collectively, the findings support a model wherein diabetes enhances REDD1-dependent activation of GSK3β to promote canonical NF-κB signaling and the development of retinal inflammation.

Small extracellular vesicles-transported lncRNA TDRKH-AS1 derived from AOPPs-treated trophoblasts initiates endothelial cells pyroptosis through PDIA4/DDIT4 axis in preeclampsia

BACKGROUND

Substantial studies have demonstrated that oxidative stress placenta and endothelial injury are considered to inextricably critical events in the pathogenesis of preeclampsia (PE). Systemic inflammatory response and endothelial dysfunction are induced by the circulating factors released from oxidative stress placentae. As a novel biomarker of oxidative stress, advanced oxidation protein products (AOPPs) levels are strongly correlated with PE characteristics. Nevertheless, the molecular mechanism underlying the effect of factors is still largely unknown.

METHODS

With the exponential knowledge on the importance of placenta-derived extracellular vesicles (pEVs), we carried out lncRNA transcriptome profiling on small EVs (sEVs) secreted from AOPPs-treated trophoblast cells and identified upregulated lncRNA TDRKH-AS1 as a potentially causative factor for PE. We isolated and characterized sEVs from plasma and trophoblast cells by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western blotting. The expression and correlation of lncRNA TDRKH-AS1 were evaluated using qRT-PCR in plasmatic sEVs and placentae from patients. Pregnant mice injected with TDRKH-AS1-riched trophoblast sEVs was performed to detect the TDRKH-AS1 function in vivo. To investigate the potential effect of sEVs-derived TDRKH-AS1 on endothelial function in vitro, transcriptome sequencing, scanning electron Microscopy (SEM), immunofluorescence, ELISA and western blotting were conducted in HUVECs. RNA pulldown, mass spectrometry, RNA immunoprecipitation (RIP), chromatin isolation by RNA purification (ChIRP) and coimmunoprecipitation (Co-IP) were used to reveal the latent mechanism of TDRKH-AS1 on endothelial injury.

RESULTS

The expression level of TDRKH-AS1 was significantly increased in plasmatic sEVs and placentae from patients, and elevated TDRKH-AS1 in plasmatic sEVs was positively correlated with clinical severity of the patients. Moreover, pregnant mice injected with TDRKH-AS1-riched trophoblast sEVs exhibited a hallmark feature of PE with increased blood pressure and systemic inflammatory responses. Pyroptosis, an inflammatory form of programmed cell death, is involved in the development of PE. Indeed, our in vitro study indicated that sEVs-derived TDRKH-AS1 secreted from AOPPs-induced trophoblast elevated DDIT4 expression levels to trigger inflammatory response of pyroptosis in endothelial cells through interacting with PDIA4.

CONCLUSIONS

Herein, results in the present study supported that TDRKH-AS1 in sEVs isolated from oxidative stress trophoblast may be implicated in the pathogenesis of PE via inducing pyroptosis and aggravating endothelial dysfunction.

GIPR expression is induced by thiazolidinediones in a PPARγ-independent manner and repressed by obesogenic stimuli

Adipose tissue (AT) dysfunctions are associated with the onset of insulin resistance (IR) and type 2 diabetes mellitus (T2DM). Targeting glucose-dependent insulinotropic peptide receptor (GIPR) is a valid option to increase the efficacy of glucagon-like peptide 1 (GLP-1) receptor agonists in T2DM treatment. Nevertheless, the therapeutic potential of targeting the GIP/GIPR axis and its effect on the AT are controversial. In this work, we explored the expression and regulation of GIPR in precursor cells and mature adipocytes, investigating if and how obesogenic stimuli and thiazolidinediones perturb GIPR expression. Using publicly available gene expression datasets, we assessed that, among white adipose tissue (WAT) cells, adipocytes express lower levels of GIPR compared to cells of mesothelial origin, pericytes, dendritic and NK/T cells. However, we report that GIPR levels markedly increase during the in vitro differentiation of both murine and human adipocytes, from 3T3-L1 and human mesenchymal precursor cells (MSCs), respectively. Notably, we demonstrated that thiazolidinediones - ie. synthetic PPARγ agonists widely used as anti-diabetic drugs and contained in the adipogenic mix - markedly induce GIPR expression. Moreover, using multiple in vitro systems, we assessed that thiazolidinediones induce GIPR in a PPARγ-independent manner. Our results support the hypothesis that PPARγ synthetic agonists may be used to increase GIPR levels in AT, potentially affecting in turn the targeting of GIP system in patients with metabolic dysfunctions. Furthermore, we demonstrate in vitro and in vivo that proinflammatory stimuli, and especially the TNFα, represses GIPR both in human and murine adipocytes, even though discordant results were obtained between human and murine cellular systems for other cytokines. Finally, we demonstrated that GIPR is negatively affected also by the excessive lipid engulfment. Overall, we report that obesogenic stimuli - ie. pro-inflammatory cytokines and the increased lipid accumulation - and PPARγ synthetic ligands oppositely modulate GIPR expression, possibly influencing the effectiveness of GIP agonists.

PERK/ATF4-dependent expression of the stress response protein REDD1 promotes proinflammatory cytokine expression in the heart of obese mice

Endoplasmic reticulum (ER) stress and inflammation are hallmarks of myocardial impairment. Here, we investigated the role of the stress response protein regulated in development and DNA damage 1 (REDD1) as a molecular link between ER stress and inflammation in cardiomyocytes. In mice fed a high-fat high-sucrose (HFHS, 42% kcal fat, 34% sucrose by weight) diet for 12 wk, REDD1 expression in the heart was increased in coordination with markers of ER stress and inflammation. In human AC16 cardiomyocytes exposed to either hyperglycemic conditions or the saturated fatty acid palmitate, REDD1 expression was increased coincident with ER stress and upregulated expression of the proinflammatory cytokines IL-1β, IL-6, and TNFα. In cardiomyocytes exposed to hyperglycemic/hyperlipidemic conditions, pharmacological inhibition of the ER kinase protein kinase RNA-like endoplasmic reticulum kinase (PERK) or knockdown of the transcription factor ATF4 prevented the increase in REDD1 expression. REDD1 deletion reduced proinflammatory cytokine expression in both cardiomyocytes exposed to hyperglycemic/hyperlipidemic conditions and in the hearts of obese mice. Overall, the findings support a model wherein HFHS diet contributes to the development of inflammation in cardiomyocytes by promoting REDD1 expression via activation of a PERK/ATF4 signaling axis.NEW & NOTEWORTHY Interplay between endoplasmic reticulum stress and inflammation contributes to cardiovascular disease progression. The studies here identify the stress response protein known as REDD1 as a missing molecular link that connects the development of endoplasmic reticulum stress with increased production of proinflammatory cytokines in the hearts of obese mice.

REDD1 deletion and treadmill running increase liver hepcidin and gluconeogenic enzymes in male mice

The iron-regulatory hormone hepcidin is transcriptionally up-regulated by gluconeogenic signals. Recent evidence suggeststhat increases in circulating hepcidin may decrease dietary iron absorption following prolonged exercise, however evidence is limited on whether gluconeogenic signals contribute to post-exercise increases in hepcidin. Mice with genetic knockout of regulated in development and DNA response-1 (REDD1) display greater glycogen depletion following exercise, possibly indicating greater gluconeogenesis. The objective of the present study was to determine liver hepcidin, markers of gluconeogenesis and iron metabolism in REDD1 knockout and wild-type mice following prolonged exercise. Twelve-week-old male REDD1 knockout and wild-type mice were randomised to rest or 60 min treadmill running with 1, 3 or 6 h recovery (n = 5-8/genotype/group). Liver gene expression of hepcidin (Hamp) and gluconeogenic enzymes (Ppargc1a, Creb3l3, Pck1, Pygl) were determined by qRT-PCR. Effects of genotype, exercise and their interaction were assessed by two-way ANOVAs with Tukey's post-hoc tests, and Pearson correlations were used to assess the relationships between Hamp and study outcomes. Liver Hamp increased 1- and 4-fold at 3 and 6 h post-exercise, compared to rest (P-adjusted < 0⋅009 for all), and was 50% greater in REDD1 knockout compared to wild-type mice (P = 0⋅0015). Liver Ppargc1a, Creb3l3 and Pck1 increased with treadmill running (P < 0⋅0001 for all), and liver Ppargc1a, Pck1 and Pygl were greater with REDD1 deletion (P < 0⋅02 for all). Liver Hamp was positively correlated with liver Creb3l3 (R = 0⋅62, P < 0⋅0001) and Pck1 (R = 0⋅44, P = 0⋅0014). In conclusion, REDD1 deletion and prolonged treadmill running increased liver Hamp and gluconeogenic regulators of Hamp, suggesting gluconeogenic signalling of hepcidin with prolonged exercise.

Stress response protein REDD1 promotes diabetes-induced retinal inflammation by sustaining canonical NF-κB signaling

Inflammation contributes to the progression of retinal pathology caused by diabetes. Here, we investigated a role for the stress response protein regulated in development and DNA damage response 1 (REDD1) in the development of retinal inflammation. Increased REDD1 expression was observed in the retina of mice after 16-weeks of streptozotocin (STZ)-induced diabetes, and REDD1 was essential for diabetes-induced pro-inflammatory cytokine expression. In human retinal MIO-M1 Müller cell cultures, REDD1 deletion prevented increased pro-inflammatory cytokine expression in response to hyperglycemic conditions. REDD1 deletion promoted nuclear factor erythroid-2-related factor 2 (Nrf2) hyperactivation; however, Nrf2 was not required for reduced inflammatory cytokine expression in REDD1-deficient cells. Rather, REDD1 enhanced inflammatory cytokine expression by promoting activation of nuclear transcription factor κB (NF-κB). In WT cells exposed to tumor necrosis factor α (TNFα), inflammatory cytokine expression was increased in coordination with activating transcription factor 4 (ATF4)-dependent REDD1 expression and sustained activation of NF-κB. In both Müller cell cultures exposed to TNFα and in the retina of STZ-diabetic mice, REDD1 deletion promoted inhibitor of κB (IκB) expression and reduced NF-κB DNA-binding activity. We found that REDD1 acted upstream of IκB by enhancing both K63-ubiquitination and auto-phosphorylation of IκB kinase complex. In contrast with STZ-diabetic REDD1^+/+ mice, IκB kinase complex autophosphorylation and macrophage infiltration were not observed in the retina of STZ-diabetic REDD1^-/- mice. The findings provide new insight into how diabetes promotes retinal inflammation and support a model wherein REDD1 sustains activation of canonical NF-κB signaling.

REDD1 promotes obesity-induced metabolic dysfunction via atypical NF-κB activation

Regulated in development and DNA damage response 1 (REDD1) expression is upregulated in response to metabolic imbalance and obesity. However, its role in obesity-associated complications is unclear. Here, we demonstrate that the REDD1-NF-κB axis is crucial for metabolic inflammation and dysregulation. Mice lacking Redd1 in the whole body or adipocytes exhibited restrained diet-induced obesity, inflammation, insulin resistance, and hepatic steatosis. Myeloid Redd1-deficient mice showed similar results, without restrained obesity and hepatic steatosis. Redd1-deficient adipose-derived stem cells lost their potential to differentiate into adipocytes; however, REDD1 overexpression stimulated preadipocyte differentiation and proinflammatory cytokine expression through atypical IKK-independent NF-κB activation by sequestering IκBα from the NF-κB/IκBα complex. REDD1 with mutated Lys^219/220Ala, key amino acid residues for IκBα binding, could not stimulate NF-κB activation, adipogenesis, and inflammation in vitro and prevented obesity-related phenotypes in knock-in mice. The REDD1-atypical NF-κB activation axis is a therapeutic target for obesity, meta-inflammation, and metabolic complications.

Nutritional Sensor REDD1 in Cancer and Inflammation: Friend or Foe?

Regulated in Development and DNA Damage Response 1 (REDD1)/DNA Damage-Induced Transcript 4 (DDIT4) is an immediate early response gene activated by different stress conditions, including growth factor depletion, hypoxia, DNA damage, and stress hormones, i.e., glucocorticoids. The most known functions of REDD1 are the inhibition of proliferative signaling and the regulation of metabolism via the repression of the central regulator of these processes, the mammalian target of rapamycin (mTOR). The involvement of REDD1 in cell growth, apoptosis, metabolism, and oxidative stress implies its role in various pathological conditions, including cancer and inflammatory diseases. Recently, REDD1 was identified as one of the central genes mechanistically involved in undesirable atrophic effects induced by chronic topical and systemic glucocorticoids widely used for the treatment of blood cancer and inflammatory diseases. In this review, we discuss the role of REDD1 in the regulation of cell signaling and processes in normal and cancer cells, its involvement in the pathogenesis of different diseases, and the approach to safer glucocorticoid receptor (GR)-targeted therapies via a combination of glucocorticoids and REDD1 inhibitors to decrease the adverse atrophogenic effects of these steroids.

Mechanisms of cancer cell death induction by paclitaxel: an updated review

Chemoresistance of cancer cells is a major problem in treating cancer. Knowledge of how cancer cells may die or resist cancer drugs is critical to providing certain strategies to overcome tumour resistance to treatment. Paclitaxel is known as a chemotherapy drug that can suppress the proliferation of cancer cells by inducing cell cycle arrest and induction of mitotic catastrophe. However, today, it is well known that paclitaxel can induce multiple kinds of cell death in cancers. Besides the induction of mitotic catastrophe that occurs during mitosis, paclitaxel has been shown to induce the expression of several pro-apoptosis mediators. It also can modulate the activity of anti-apoptosis mediators. However, certain cell-killing mechanisms such as senescence and autophagy can increase resistance to paclitaxel. This review focuses on the mechanisms of cell death, including apoptosis, mitotic catastrophe, senescence, autophagic cell death, pyroptosis, etc., following paclitaxel treatment. In addition, mechanisms of resistance to cell death due to exposure to paclitaxel and the use of combinations to overcome drug resistance will be discussed.

Comparative transcriptome analysis reveals immunoregulation mechanism of lncRNA-mRNA in gill and skin of large yellow croaker (Larimichthys crocea) in response to Cryptocaryon irritans infection

Background

Cryptocaryonosis caused by Cryptocaryon irritans is one of the major diseases of large yellow croaker (Larimichthys crocea), which lead to massive economic losses annually to the aquaculture industry of L. crocea. Although there have been some studies on the pathogenesis for cryptocaryonosis, little is known about the innate defense mechanism of different immune organs of large yellow croaker.

Results

In order to analyze the roles of long non-coding RNAs and genes specifically expressed between immune organs during the infection of C. irritans, in this study, by comparing transcriptome data from different tissues of L. crocea, we identified tissue-specific transcripts in the gills and skin, including 507 DE lncRNAs and 1592 DEGs identified in the gills, and 110 DE lncRNAs and 1160 DEGs identified in the skin. Furthermore, we constructed transcriptome co-expression profiles of L. crocea gill and skin, including 7,503 long noncoding RNAs (lncRNAs) and 23,172 protein-coding genes. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that the DEGs and the target genes of the DE lncRNAs in the gill were specifically enriched in several pathways related to immune such as HIF-1 signaling pathway. The target genes of DE lncRNAs and DEGs in the skin are specifically enriched in the complement and coagulation cascade pathways. Protein–protein interaction (PPI) network analysis identified 3 hub genes including NFKBIA, TNFAIP3 and CEBPB, and 5 important DE lncRNAs including MSTRG.24134.4, MSTRG.3038.5, MSTRG.27019.3, MSTRG.26559.1, and MSTRG.10983.1. The expression patterns of 6 randomly selected differentially expressed immune-related genes were validated using the quantitative real-time PCR method.

Conclusions

In short, our study is helpful to explore the potential interplay between lncRNAs and protein coding genes in different tissues of L. crocea post C. irritans and the molecular mechanism of pathogenesis for cryptocaryonosis.

Highlights

Skin and gills are important sources of pro-inflammatory molecules, and their gene expression patterns are tissue-specific after C. irritans infection.

15 DEGs and 5 DE lncRNAs were identified as hub regulatory elements after C. irritans infection

The HIF-1 signaling pathway and the complement and coagulation cascade pathway may be key tissue-specific regulatory pathways in gills and skin, respectively.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08431-w.

Long Non-coding Antisense RNA DDIT4-AS1 Regulates Meningitic Escherichia coli-Induced Neuroinflammation by Promoting DDIT4 mRNA Stability

Our previous studies have shown that meningitic Escherichia coli can colonize the brain and cause neuroinflammation. Controlling the balance of inflammatory responses in the host central nervous system is particularly vital. Emerging evidence has shown the important regulatory roles of long non-coding RNAs (lncRNAs) in a wide range of biological and pathological processes. However, whether lncRNAs participate in the regulation of meningitic E. coli-mediated neuroinflammation remains unknown. In the present study, we characterized a cytoplasm-enriched antisense lncRNA DDIT4-AS1, which showed similar concordant expression patterns with its parental mRNA DDIT4 upon E. coli infection. DDIT4-AS1 modulated DDIT4 expression at both mRNA and protein levels. Mechanistically, DDIT4-AS1 promoted the stability of DDIT4 mRNA through RNA duplex formation. DDIT4-AS1 knockdown and DDIT4 knockout both attenuated E. coli-induced NF-κB signaling as well as pro-inflammatory cytokines expression, and DDIT4-AS1 regulated the inflammatory response by targeting DDIT4. In summary, our results show that DDIT4-AS1 promotes E. coli-induced neuroinflammatory responses by enhancing the stability of DDIT4 mRNA through RNA duplex formation, providing potential nucleic acid targets for new therapeutic interventions in the treatment of bacterial meningitis.

RTP801/REDD1 Is Involved in Neuroinflammation and Modulates Cognitive Dysfunction in Huntington's Disease

RTP801/REDD1 is a stress-regulated protein whose levels are increased in several neurodegenerative diseases such as Parkinson's, Alzheimer's, and Huntington's diseases (HD). RTP801 downregulation ameliorates behavioral abnormalities in several mouse models of these disorders. In HD, RTP801 mediates mutant huntingtin (mhtt) toxicity in in vitro models and its levels are increased in human iPSCs, human postmortem putamen samples, and in striatal synaptosomes from mouse models of the disease. Here, we investigated the role of RTP801 in the hippocampal pathophysiology of HD. We found that RTP801 levels are increased in the hippocampus of HD patients in correlation with gliosis markers. Although RTP801 expression is not altered in the hippocampus of the R6/1 mouse model of HD, neuronal RTP801 silencing in the dorsal hippocampus with shRNA containing AAV particles ameliorates cognitive alterations. This recovery is associated with a partial rescue of synaptic markers and with a reduction in inflammatory events, especially microgliosis. Altogether, our results indicate that RTP801 could be a marker of hippocampal neuroinflammation in HD patients and a promising therapeutic target of the disease.

TNFα Mediates Inflammation-Induced Effects on PPARG Splicing in Adipose Tissue and Mesenchymal Precursor Cells

Low-grade chronic inflammation and reduced differentiation capacity are hallmarks of hypertrophic adipose tissue (AT) and key contributors of insulin resistance. We identified PPARGΔ5 as a dominant-negative splicing isoform overexpressed in the AT of obese/diabetic patients able to impair adipocyte differentiation and PPARγ activity in hypertrophic adipocytes. Herein, we investigate the impact of macrophage-secreted pro-inflammatory factors on PPARG splicing, focusing on PPARGΔ5. We report that the epididymal AT of LPS-treated mice displays increased PpargΔ5/cPparg ratio and reduced expression of Pparg-regulated genes. Interestingly, pro-inflammatory factors secreted from murine and human pro-inflammatory macrophages enhance the PPARGΔ5/cPPARG ratio in exposed adipogenic precursors. TNFα is identified herein as factor able to alter PPARG splicing—increasing PPARGΔ5/cPPARG ratio—through PI3K/Akt signaling and SRp40 splicing factor. In line with in vitro data, TNFA expression is higher in the SAT of obese (vs. lean) patients and positively correlates with PPARGΔ5 levels. In conclusion, our results indicate that inflammatory factors secreted by metabolically-activated macrophages are potent stimuli that modulate the expression and splicing of PPARG. The resulting imbalance between canonical and dominant negative isoforms may crucially contribute to impair PPARγ activity in hypertrophic AT, exacerbating the defective adipogenic capacity of precursor cells.

Early Stress-Response Gene REDD1 Controls Oxazolone-Induced Allergic Contact Dermatitis

REDD1 is an energy sensor and stress-induced mTOR inhibitor. Recently, its novel role in linking metabolism and inflammation/immune responses has emerged. In this study, we assessed the role of REDD1 in murine oxazolone-induced allergic contact dermatitis (ACD), a T cell-dependent model with features of human ACD. A variety of immune indices, including edema, cellular infiltration, inflammatory gene expression, and glucocorticoid response, were compared in Redd1 knockout (KO) and isogenic (C57BL/6 × 129)F1 wild-type mice after sensitization and subsequent ear challenge with oxazolone. Despite relatively normal thymic profiles and similar T cell populations in the lymph nodes of naive Redd1 KO mice, early T cell expansion and cytokine production were profoundly impaired after sensitization. Surprisingly, higher steady-state populations of CD4⁺ and CD8⁺ T cells, as well as macrophages (CD45⁺/Ly-6G^-/CD11b⁺), dendritic cells (CD45⁺/Ly-6G^-/CD11c⁺), neutrophils (CD45⁺/Ly-6G⁺/CD11b⁺), and innate lymphoid cells (CD45⁺/Lineage^-/IL-7Ra⁺/ST2⁺/c-Kit⁺), were observed in the ears of naive Redd1 KO mice. Upon challenge, ear edema, T cell, macrophage, neutrophil, and dendritic cell infiltration into the ear was significantly reduced in Redd1 KO animals. Accordingly, we observed significantly lower induction of IFN-γ, IL-4, and other cytokines as well as proinflammatory factors, including TSLP, IL-33, IL-1β, IL-6, and TNF-α, in challenged ears of Redd1 KO mice. The response to glucocorticoid treatment was also diminished. Taken together, these data establish REDD1 as an essential immune modulator that influences both the initiation of ACD disease, by driving naive T cell activation, and the effector phase, by promoting immune cell trafficking in T cell-mediated skin inflammation.

β-Caryophyllene attenuates lipopolysaccharide-induced acute lung injury via inhibition of the MAPK signalling pathway

OBJECTIVES

Acute lung injury (ALI) is a pulmonary manifestation of an acute systemic inflammatory response, which is associated with high morbidity and mortality. Accordingly, from the perspective of treating ALI, it is important to identify effective agents and elucidate the underlying modulatory mechanisms. β-Caryophyllene (BCP) is a naturally occurring bicyclic sesquiterpene that has anti-cancer and anti-inflammatory activities. However, the effects of BCP on ALI have yet to be ascertained.

METHODS

ALI was induced intratracheally, injected with 5 mg/kg LPS and treated with BCP. The bone marrow-derived macrophages (BMDMs) were obtained and cultured then challenged with 100 ng/ml LPS for 4 h, with or without BCP pre-treatment for 30 min.

KEY FINDINGS

BCP significantly ameliorates LPS-induced mouse ALI, which is related to an alleviation of neutrophil infiltration and reduction in cytokine production. In vitro, BCP was found to reduce the expression of interleukin-6, interleukin-1β and tumour necrosis factor-α, and suppresses the MAPK signalling pathway in BMDMs, which is associated with the inhibition of TAK1 phosphorylation and an enhancement of MKP-1 expression.

CONCLUSIONS

Our data indicate that BCP protects against inflammatory responses and is a potential therapeutic agent for the treatment of LPS-induced acute lung injury.

Chemotherapy-Induced Myopathy: The Dark Side of the Cachexia Sphere

Simple Summary

In addition to cancer-related factors, anti-cancer chemotherapy treatment can drive life-threatening body wasting in a syndrome known as cachexia. Emerging evidence has described the impact of several key chemotherapeutic agents on skeletal muscle in particular, and the mechanisms are gradually being unravelled. Despite this evidence, there remains very little research regarding therapeutic strategies to protect muscle during anti-cancer treatment and current global grand challenges focused on deciphering the cachexia conundrum fail to consider this aspect—chemotherapy-induced myopathy remains very much on the dark side of the cachexia sphere. This review explores the impact and mechanisms of, and current investigative strategies to protect against, chemotherapy-induced myopathy to illuminate this serious issue.

Abstract

Cancer cachexia is a debilitating multi-factorial wasting syndrome characterised by severe skeletal muscle wasting and dysfunction (i.e., myopathy). In the oncology setting, cachexia arises from synergistic insults from both cancer–host interactions and chemotherapy-related toxicity. The majority of studies have surrounded the cancer–host interaction side of cancer cachexia, often overlooking the capability of chemotherapy to induce cachectic myopathy. Accumulating evidence in experimental models of cachexia suggests that some chemotherapeutic agents rapidly induce cachectic myopathy, although the underlying mechanisms responsible vary between agents. Importantly, we highlight the capacity of specific chemotherapeutic agents to induce cachectic myopathy, as not all chemotherapies have been evaluated for cachexia-inducing properties—alone or in clinically compatible regimens. Furthermore, we discuss the experimental evidence surrounding therapeutic strategies that have been evaluated in chemotherapy-induced cachexia models, with particular focus on exercise interventions and adjuvant therapeutic candidates targeted at the mitochondria.

RTP801/REDD1 contributes to neuroinflammation severity and memory impairments in Alzheimer's disease

RTP801/REDD1 is a stress-regulated protein whose upregulation is necessary and sufficient to trigger neuronal death. Its downregulation in Parkinson's and Huntington's disease models ameliorates the pathological phenotypes. In the context of Alzheimer's disease (AD), the coding gene for RTP801, DDIT4, is responsive to Aβ and modulates its cytotoxicity in vitro. Also, RTP801 mRNA levels are increased in AD patients' lymphocytes. However, the involvement of RTP801 in the pathophysiology of AD has not been yet tested. Here, we demonstrate that RTP801 levels are increased in postmortem hippocampal samples from AD patients. Interestingly, RTP801 protein levels correlated with both Braak and Thal stages of the disease and with GFAP expression. RTP801 levels are also upregulated in hippocampal synaptosomal fractions obtained from murine 5xFAD and rTg4510 mice models of the disease. A local RTP801 knockdown in the 5xFAD hippocampal neurons with shRNA-containing AAV particles ameliorates cognitive deficits in 7-month-old animals. Upon RTP801 silencing in the 5xFAD mice, no major changes were detected in hippocampal synaptic markers or spine density. Importantly, we found an unanticipated recovery of several gliosis hallmarks and inflammasome key proteins upon neuronal RTP801 downregulation in the 5xFAD mice. Altogether our results suggest that RTP801 could be a potential future target for theranostic studies since it could be a biomarker of neuroinflammation and neurotoxicity severity of the disease and, at the same time, a promising therapeutic target in the treatment of AD.

Familial Mediterranean fever: the molecular pathways from stress exposure to attacks

FMF is an autoinflammatory disease characterized by recurrent attacks and increased IL-1 synthesis owing to activation of the pyrin inflammasome. Although knowledge of the mechanisms leading to the activation of pyrin inflammasome is increasing, it is still unknown why the disease is characterized by attack. The emergence of FMF attacks after emotional stress and the induction of attacks with metaraminol in previous decades suggested that stress-induced sympathoadrenal system activation might play a role in inflammasome activation and triggering attacks. In this review, we will review the possible molecular mechanism of stress mediators on the inflammation pathway and inflammasome activation. Studies on stress mediators and their impact on inflammation pathways will provide a better understanding of stress-related exacerbation mechanisms in both autoinflammatory and autoimmune diseases. This review provides a new perspective on this subject and will contribute to new studies.

Cellular, Molecular and Biochemical Impacts of Silver Nanoparticles on Rat Cerebellar Cortex

BACKGROUND

The excessive exposure to silver nanoparticles (Ag-NPs) has raised concerns about their possible risks to the human health. The brain is a highly vulnerable organ to nano-silver harmfulness. The aim of this work was to evaluate the impacts of Ag-NPs exposure on the cerebellar cortex of rats.

METHODS

Rats were assigned to: Control, vehicle control and Ag-NP-exposed groups (at doses of 10 mg and 30 mg/kg/day). Samples were processed for light and electron microscopy examinations. Immunohistochemical localization of c-Jun N-terminal kinase (JNK), nuclear factor kappa beta (NF-κB) and calbindin D28k (CB) proteins was performed. Analyses of expression of DNA damage inducible transcript 4 (Ddit4), flavin containing monooxygenase 2 (FMO2) and thioredoxin-interacting protein (Txnip) genes were done. Serum levels of inflammatory cytokines were also measured.

RESULTS

Ag-NPs enhanced apoptosis as evident by upregulation of Ddit4 gene expressions and JNK protein immune expressions. Alterations of redox homeostasis were verified by enhancement of Txnip and FMO2 gene expressions, favoring the activation of inflammatory responses by increasing NF-κB protein immune expressions and serum inflammatory mediator levels. Another cytotoxic effect was the reduction of immune expressions of the calcium regulator CB.

CONCLUSION

Ag-NPs exposure provoked biochemical, cellular and molecular changes of rat cerebellar cortex in a dose-dependent manner.

REDD1 Is Involved in Amyloid β-Induced Synaptic Dysfunction and Memory Impairment

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by neurological dysfunction, including memory impairment, attributed to the accumulation of amyloid β (Aβ) in the brain. Although several studies reported possible mechanisms involved in Aβ pathology, much remains unknown. Previous findings suggested that a protein regulated in development and DNA damage response 1 (REDD1), a stress-coping regulator, is an Aβ-responsive gene involved in Aβ cytotoxicity. However, we still do not know how Aβ increases the level of REDD1 and whether REDD1 mediates Aβ-induced synaptic dysfunction. To elucidate this, we examined the effect of Aβ on REDD1-expression using acute hippocampal slices from mice, and the effect of REDD1 short hairpin RNA (shRNA) on Aβ-induced synaptic dysfunction. Lastly, we observed the effect of REDD1 shRNA on memory deficit in an AD-like mouse model. Through the experiments, we found that Aβ-incubated acute hippocampal slices showed increased REDD1 levels. Moreover, Aβ injection into the lateral ventricle increased REDD1 levels in the hippocampus. Anisomycin, but not actinomycin D, blocked Aβ-induced increase in REDD1 levels in the acute hippocampal slices, suggesting that Aβ may increase REDD1 translation rather than transcription. Aβ activated Fyn/ERK/S6 cascade, and inhibitors for Fyn/ERK/S6 or mGluR5 blocked Aβ-induced REDD1 upregulation. REDD1 inducer, a transcriptional activator, and Aβ blocked synaptic plasticity in the acute hippocampal slices. REDD1 inducer inhibited mTOR/Akt signaling. REDD1 shRNA blocked Aβ-induced synaptic deficits. REDD1 shRNA also blocked Aβ-induced memory deficits in passive-avoidance and object-recognition tests. Collectively, these results demonstrate that REDD1 participates in Aβ pathology and could be a target for AD therapy.

Is REDD1 a metabolic double agent? Lessons from physiology and pathology

The Akt/mechanistic target of rapamycin (mTOR) signaling pathway governs macromolecule synthesis, cell growth, and metabolism in response to nutrients and growth factors. Regulated in development and DNA damage response (REDD)1 is a conserved and ubiquitous protein, which is transiently induced in response to multiple stimuli. Acting like an endogenous inhibitor of the Akt/mTOR signaling pathway, REDD1 protein has been shown to regulate cell growth, mitochondrial function, oxidative stress, and apoptosis. Recent studies also indicate that timely REDD1 expression limits Akt/mTOR-dependent synthesis processes to spare energy during metabolic stresses, avoiding energy collapse and detrimental consequences. In contrast to this beneficial role for metabolic adaptation, REDD1 chronic expression appears involved in the pathogenesis of several diseases. Indeed, REDD1 expression is found as an early biomarker in many pathologies including inflammatory diseases, cancer, neurodegenerative disorders, depression, diabetes, and obesity. Moreover, prolonged REDD1 expression is associated with cell apoptosis, excessive reactive oxygen species (ROS) production, and inflammation activation leading to tissue damage. In this review, we decipher several mechanisms that make REDD1 a likely metabolic double agent depending on its duration of expression in different physiological and pathological contexts. We also discuss the role played by REDD1 in the cross talk between the Akt/mTOR signaling pathway and the energetic metabolism.

Global gene expression profile of periodontal ligament cells submitted to mechanical loading: A systematic review

OBJECTIVE

To evaluate the evidence reporting gene expression array data of human in vitro cultured periodontal ligament cells (PDLCs) submitted to static mechanical loading compared to a control group.

DESIGN

Systematic searches were performed in MEDLINE/PubMed, Scopus, Web of Science, Virtual Health Library, The Cochrane Library and the System for Information on Grey Literature in Europe up to June 2019. A narrative synthesis was performed to summarize differentially expressed genes (DEGs). These were grouped according to the culture method (2D or 3D), force type (compression or tension) and observation time. Additionally, gene ontology (GO) analysis was performed using the Database for Annotation Visualization and Integrated Discovery. The risk of bias (RoB) and certainty of evidence (CoE) were assessed using a modified CONSORT checklist and the GRADE tool, respectively.

RESULTS

Of eight studies included (all rated as having moderate RoB), only two provided the complete list of DEGs and four studies performed GO, gene network or pathways analysis. "Cell proliferation", "cell-cell signaling", "response to hypoxia and to mechanical stimulus" were among the significantly enriched biological processes in 3D-cultured compressed PDLCs (moderate CoE); while "collagen catabolic process", "extracellular matrix organization" and "cell proliferation" were associated with DEGs of 3D-cultured PDLCs submitted to tension (very low CoE). Biological processes significantly enriched in 2D-cultured PDLCs under compression were "extracellular matrix organization", "canonical glycolysis" and "glycolytic process" (very low CoE).

CONCLUSION

Genes such as NR4A2, NR4A3, NAMPT, PGK1, and REDD1 are suggested as novel biomarkers for orthodontic tooth movement. Limited amount of evidence on the complete gene expression profile and the high heterogeneity in methodologies make it impossible to obtain definite conclusions. New studies following standardized and well-designed in vitro model and reporting complete gene expression datasets are needed.

Albendazole-Schisandrin B Co-Therapy on Angiostrongylus cantonensis-Induced Meningoencephalitis in Mice

Currently, Angiostrongylus cantonensis infections are predominantly treated with albendazole. However, the use of albendazole can provoke certain neurological symptoms as a result of the immune response triggered by the dead worms. Therefore, treatment usually involves co-administration of corticosteroids to limit the inflammatory reaction. Corticosteroids play a useful role in suppressing inflammation in the brain; however, long-term usage or high dosage may make it problematic.Schisandrin B, an active ingredient from Schisandra chinensis, has been shown to have anti-inflammatory effects on the brain. This study aimed to investigate the effects and potential of schisandrin B in combination with albendazole to treat Angiostrongylus-induced meningoencephalitis. Here, we show that albendazole-schisandrin B co-treatment suppressed neuroinflammation in Angiostrongylus-infected mice and increased the survival of the mice. Accordingly, albendazole-schisandrin B co-treatment significantly inhibited inflammasome activation, pyroptosis, and apoptosis. The sensorimotor functions of the mice were also repaired after albendazole-schisandrin B treatment. Immune response was shown to shift from Th2 to Th1, which reduces inflammation and enhances immunity against A. cantonensis. Collectively, our study showed that albendazole-schisandrin B co-therapy may be used as an encouraging treatment for Angiostrongylus-induced meningoencephalitis.

ER Stress Activates the NLRP3 Inflammasome: A Novel Mechanism of Atherosclerosis

The endoplasmic reticulum (ER) is an important organelle that regulates several fundamental cellular processes, and ER dysfunction has implications for many intracellular events. The nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome is an intracellularly produced macromolecular complex that can trigger pyroptosis and inflammation, and its activation is induced by a variety of signals. ER stress has been found to affect NLRP3 inflammasome activation through multiple effects including the unfolded protein response (UPR), calcium or lipid metabolism, and reactive oxygen species (ROS) generation. Intriguingly, the role of ER stress in inflammasome activation has not attracted a great deal of attention. In addition, increasing evidence highlights that both ER stress and NLRP3 inflammasome activation contribute to atherosclerosis (AS). AS is a common cardiovascular disease with complex pathogenesis, and the precise mechanisms behind its pathogenesis remain to be determined. Both ER stress and the NLRP3 inflammasome have emerged as critical individual contributors of AS, and owing to the multiple associations between these two events, we speculate that they contribute to the mechanisms of pathogenesis in AS. In this review, we aim to summarize the molecular mechanisms of ER stress, NLRP3 inflammasome activation, and the cross talk between these two pathways in AS in the hopes of providing new pharmacological targets for AS treatment.

Therapeutic effects of iNOS inhibition against vitiligo in an animal model

Nitric oxide (NO) is involved in several biological processes, but its role in human melanogenesis and vitiligo need further studies. Previous studies revealed that exposure to UVA and UVB were capable of the inducing nitric oxide production in keratinocytes and melanocytes through the activation of constitutive nitric oxide synthase, whereas inducible nitric oxide synthase overexpression has been reported to play an important role in hyperpigmentary disorders. The aim of this study was to evaluate iNOS inhibitor aminoguanidine (AG) as a therapeutic agent in our mouse model of vitiligo. In this study, male C57BL/6J Ler-vit/vit mice were purchased to evaluate the effect of iNOS inhibitor (aminoguanidine) (50 and 100 mg/kg) and L-arginine (100 mg/kg) in a mouse model of vitiligo induced by monobenzone 40%. Moreover, we used phototherapy device to treat the mice with NBUVB as a gold standard.The findings revealed that monobenzone was capable of inducing depigmentation after 6 weeks. However, aminoguanidine in combination with monobenzone was decrease the effect of monobenzone, while L-arginine play a key role in promoting the effect of monobenzone (P<0.001). Based on the phototherapy, the efficacy of phototherapy significantly increased by adding L-arginine (P<0.05). Taken together, we suggest that iNOS inhibitor can be a novel treatment for the prevention and treatment of vitiligo by combination of NBUVB therapy, furthermore; NO agents like L-arginine could also increase the effectiveness of phototherapy. Taken together, this pilot study showed significant repigmentation of vitiligous lesions treated with iNOS inhibitor plus NBUVB therapy, where other aspect including expression of an inducible iNOS, NO and TNF levels remained to be evaluated in mice model.

Suppression of REDD1 attenuates oxygen glucose deprivation/reoxygenation-evoked ischemic injury in neuron by suppressing mTOR-mediated excessive autophagy

Cerebral ischemia/reperfusion (I/R) typically occurs after mechanical thrombectomy to treat ischemic stroke, generation of reactive oxygen species (ROS) after reperfusion may result in neuronal insult, ultimately leading to disability and death. Regulated in development and DNA damage responses 1 (REDD1) is a conserved stress response protein under various pathogenic conditions. Recent research confirms the controversial role of REDD1 in injury processes. Nevertheless, the role of REDD1 in cerebral I/R remains poorly defined. In the current study, increased expression of REDD1 was observed in neurons exposed to simulated I/R via oxygen glucose deprivation/reoxygenation (OGD/R) treatment. Knockdown of REDD1 enhanced OGD/R-inhibited cell viability, but suppressed lactate dehydrogenase (LDH) release in neurons upon OGD/R. Simultaneously, suppression of REDD1 also antagonized OGD/R-evoked cell apoptosis, Bax expression, and caspase-3 activity. Intriguingly, REDD1 depression abrogated neuronal oxidative stress under OGD/R condition by suppressing ROS, MDA generation, and increasing antioxidant SOD levels. Further mechanism analysis corroborated the excessive activation of autophagy in neurons upon OGD/R with increased expression of autophagy-related LC3 and Beclin-1, but decreased autophagy substrate p62 expression. Notably, REDD1 inhibition reversed OGD/R-triggered excessive neuronal autophagy. More importantly, depression of REDD1 also elevated the expression of p-mTOR. Preconditioning with mTOR inhibitor rapamycin engendered not only a reduction in mTOR activation, but also a reactivation of autophagy in REDD1 knockdown-neurons upon OGD/R. In addition, blocking the mTOR pathway muted the protective roles of REDD1 inhibition against OGD/R-induced neuron injury and oxidative stress. Together these data suggested that REDD1 may regulate I/R-induced oxidative stress injury in neurons by mediating mTOR-autophagy signaling, supporting a promising therapeutic strategy against brain ischemic diseases.

Selenium supplementation suppresses immunological and serological features of lupus in B6.Sle1b mice

Systemic lupus erythematosus (SLE) is a debilitating multi-factorial immunological disorder characterized by increased inflammation and development of anti-nuclear autoantibodies. Selenium (Se) is an essential trace element with beneficial anti-cancer and anti-inflammatory immunological functions. In our previous proteomics study, analysis of Se-responsive markers in the circulation of Se-supplemented healthy men showed a significant increase in complement proteins. Additionally, Se supplementation prolonged the life span of lupus prone NZB/NZW-F1 mice. To better understand the protective immunological role of Se in SLE pathogenesis, we have investigated the impact of Se on B cells and macrophages using in vitro Se supplementation assays and the B6.Sle1b mouse model of lupus with an oral Se or placebo supplementation regimen. Analysis of Se-treated B6.Sle1b mice showed reduced splenomegaly and splenic cellularity compared to untreated B6. Sle1b mice. A significant reduction in total B cells and notably germinal center (GC) B cell numbers was observed. However, other cell types including T cells, Tregs, DCs and pDCs were unaffected. Consistent with reduced GC B cells there was a significant reduction in autoantibodies to dsDNA and SmRNP of the IgG2b and IgG2c subclass upon Se supplementation. We found that increased Se availability leads to impaired differentiation and maturation of macrophages from mouse bone marrow derived progenitors in vitro. Additionally, Se treatment during in vitro activation of B cells with anti-CD40L and LPS inhibited optimal B cell activation. Overall our data indicate that Se supplementation inhibits activation, differentiation and maturation of B cells and macrophages. Its specific inhibitory effect on B cell activation and GC B cell differentiation could be explored as a potential therapeutic supplement for SLE patients.

Blocking the REDD1/TXNIP axis ameliorates LPS-induced vascular endothelial cell injury through repressing oxidative stress and apoptosis

The aim of the present study was to investigate the potential role of regulated in development and DNA damage response 1 (REDD1) in LPS-induced vascular endothelial injury by using human umbilical vein endothelial cells (HUVECs). We observed that REDD1 expression was apparently elevated in HUVECs after exposure to LPS. Additionally, elimination of REDD1 strikingly attenuated the secretion of the proinflammatory cytokines TNF-α, IL-6, IL-1β, and monocyte chemotactic protein-1 and the endothelial cell adhesion markers ICAM-1 and VCAM-1 that was induced by LPS stimulation. Subsequently, knockdown of REDD1 augmented cell viability but ameliorated lactate dehydrogenase release in HUVECs stimulated with LPS. Meanwhile, depletion of REDD1 effectively restricted LPS-induced HUVEC apoptosis, as exemplified by reduced DNA fragmentation, and it also elevated antiapoptotic Bcl-2 protein, concomitant with reduced levels of proapoptotic proteins Bax and cleaved caspase-3. Furthermore, repression of REDD1 remarkably alleviated LPS-triggered intracellular reactive oxygen species generation accompanied by decreased malondialdehyde content and increased the activity of the endogenous antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase. Most important, depletion of REDD1 protected HUVECs against inflammation-mediated apoptosis and oxidative damage partly through thioredoxin-interacting protein (TXNIP). Collectively, these findings indicate that blocking the REDD1/TXNIP axis repressed the inflammation-mediated vascular injury process, which may be closely related to oxidative stress and apoptosis in HUVECs, implying that the REDD1/TXNIP axis may be a new target for preventing the endothelial cell injury process.

Targeting hepatic miR-221/222 for therapeutic intervention of nonalcoholic steatohepatitis in mice

Background

Effective targeting therapies for common chronic liver disease nonalcoholic steatohepatitis (NASH) are in urgent need. MicroRNA-targeted therapeutics would be potentially an effective treatment strategy of hepatic diseases. Here we investigated the functional role of miR-221/222 and the therapeutic effects of antimiRs-221/222 in NASH mouse models.

Methods

We generated the miR-221/222^flox/flox mice on a C57BL/6 J background and the hepatic miR-221/222 knockout (miR-221/222-LKO) mice. The mice were challenged with the methionine and choline deficient diet (MCDD) or chronic carbon tetrachloride (CCl₄) treatment to generate experimental steatohepatitis models. Adenovirus-mediated re-expression of miR-221/222 was performed on the MCDD-fed miR-221/222-LKO mice. The MCDD and control diet-fed mice were treated with locked nucleic acid (LNA)-based antimiRs of miR-221/222 to evaluate the therapeutic effects. Histological analysis, RNA-seq, quantitative PCR and Western blot of liver tissues were carried out to study the hepatic lipid accumulation, inflammation and collagen deposition in mouse models.

Findings

Hepatic deletion of miR-221/222 resulted in significant reduction of liver fibrosis, lipid deposition and inflammatory infiltration in the MCDD-fed and CCl4-treated mouse models. The hepatic steatosis and fibrosis were dramatically aggravated by miR-221/222 re-expression in MCDD-fed miR-221/222-LKO mice. AntimiRs of miR-221/222 could effectively reduce the MCDD-mediated hepatic steatosis and fibrosis. Systematically mechanistic study revealed that hepatic miR-221/222 controlled the expression of target gene Timp3 and promoted the progression of NASH.

Interpretation

Our findings demonstrate that miR-221/222 are crucial for the regulation of lipid metabolism, inflammation and fibrosis in the liver. LNA-antimiRs targeted miR-221/222 could reduce steatohepatitis with prominent antifibrotic effect in NASH mice.

Fund

This work is supported by the Natural Science Foundation of China (81530020, 81390352 to Dr. Ning and 81522032 to Dr. Cao and 81670793 to Dr. Jiang); National Key Research and Development Program (No. 2016YFC0905001 and 2017YFC0909703 to Dr. Cao); the Shanghai Rising-Star Program (15QA1402900 to Dr. Cao); Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant (20171905 to Dr. Jiang).

Autophagy in Neutrophils: From Granulopoiesis to Neutrophil Extracellular Traps

Autophagy is an evolutionarily conserved intracellular degradation system aiming to maintain cell homeostasis in response to cellular stress. At physiological states, basal or constitutive level of autophagy activity is usually low; however, it is markedly up-regulated in response to oxidative stress, nutrient starvation, and various immunological stimuli including pathogens. Many studies over the last years have indicated the implication of autophagy in a plethora of cell populations and functions. In this review, we focus on the role of autophagy in the biology of neutrophils. Early studies provided a link between autophagy and neutrophil cell death, a process essential for resolution of inflammation. Since then, several lines of evidence both in the human system and in murine models propose a critical role for autophagy in neutrophil-driven inflammation and defense against pathogens. Autophagy is essential for major neutrophil functions, including degranulation, reactive oxygen species production, and release of neutrophil extracellular traps. Going back to neutrophil generation in the bone marrow, autophagy plays a critical role in myelopoiesis, driving the differentiation of progenitor cells of the myeloid lineage toward neutrophils. Taken together, in this review we discuss the functional role of autophagy in neutrophils throughout their life, from their production in the bone marrow to inflammatory responses and NETotic cell death.

mTORC1 pathway in DNA damage response

Living organisms have evolved various mechanisms to control their metabolism and response to various stresses, allowing them to survive and grow in different environments. In eukaryotes, the highly conserved mechanistic target of rapamycin (mTOR) signaling pathway integrates both intracellular and extracellular signals and serves as a central regulator of cellular metabolism, proliferation and survival. A growing body of evidence indicates that mTOR signaling is closely related to another cellular protection mechanism, the DNA damage response (DDR). Many factors important for the DDR are also involved in the mTOR pathway. In this review, we discuss how these two pathways communicate to ensure an efficient protection of the cell against metabolic and genotoxic stresses. We also describe how anticancer therapies benefit from simultaneous targeting of the DDR and mTOR pathways.

REDD-1 aggravates endotoxin-induced inflammation via atypical NF-κB activation

Regulated in development and DNA damage responses 1 (REDD-1), an inhibitor of mammalian target of rapamycin (mTOR), is induced by various cell stressors, including LPS, a major player in the pathogenesis of endotoxemic shock. However, the pathologic role of REDD-1 in endotoxemia is largely unknown. We found that LPS increased REDD-1 expression, nuclear transcription factor-κB (NF-κB) activation, and inflammation and that these responses were suppressed by REDD-1 knockdown and in REDD-1^+/- macrophages. REDD-1 overexpression stimulated NF-κB-dependent inflammation without additional LPS stimulation. REDD-1-induced NF-κB activation was independent of 2 classic IKK-dependent NF-κB pathways and the mTOR signaling pathway; however, REDD-1, particularly its C-terminal region (178-229), interacted with and sequestered IκBα, to elicit atypical NF-κB activation during the delayed and persistent phases of inflammation after stimulation. Moreover, REDD-1 knockdown mitigated vascular inflammation and permeability in endotoxemic mice, resulting in decreases in immune cell infiltration, systemic inflammation, caspase-3 activation, apoptosis, and consequent mortality. We further confirmed the inflammatory and cytotoxic effects of REDD-1 in endotoxemic REDD-1^+/- mice. Our data support the likelihood that REDD-1 exacerbates endotoxemic inflammation via atypical NF-κB activation by sequestering IκBα.-Lee, D.-K., Kim, J.-H., Kim, J., Choi, S., Park, M., Park, W., Kim, S., Lee, K.-S., Kim, T., Jung, J., Choi, Y. K., Ha, K.-S., Won, M.-H., Billiar, T. R., Kwon, Y.-G., Kim, Y.-M. REDD-1 aggravates endotoxin-induced inflammation via atypical NF-κB activation.

Inflammatory response and oxidative stress during liver resection

Background

Postoperative complications are still a major concern after liver resection (LR). Systemic inflammation and deregulated reactive oxygen species during major abdominal surgery may impair outcome after hepatectomy.

Methods

Patients undergoing LR were included in this study (n = 40). Oxidative stress (OS) was measured peri- and post-operatively as static oxidation-reduction potential markers (sORP) and antioxidant capacity ORP (cORP) by using the RedoxSYS Diagnostic system. Furthermore, Th1- and Th2-specific cytokines were assessed.

Results

Whereas there was no significant change in systemic sORP during LR and in the early postoperative course, there was a substantial decrease of cORP immediately post-surgery, and on postoperative days 1 and 3 (p<0.001). OS response was tightly regulated, as there was a significant correlation between sORP and cORP (p<0.0001; R²:0.457). An increase of OS (sORP) after LR of more than 3 mV was predictive for severe postoperative complications (53.8% vs. 12.5; p = 0.017). There was a significantly higher IL-2 (p = 0.006) and IL-5 (p = 0.001) increase during hepatectomy in patients who developed a severe morbidity.

Conclusion

Antioxidant capacity remained stable during LR but dropped during the post-surgical period, suggesting a consumption of antioxidants to maintain OS within healthy range. Severe postoperative complications were associated with a pronounced inflammatory response during surgery.