Mitochondrial Sirtuin 4 Resolves Immune Tolerance in Monocytes by Rebalancing Glycolysis and Glucose Oxidation Homeostasis

Autophagy-related molecular clusters identified as indicators for distinguishing active and latent TB infection in pediatric patients

BACKGROUND

Autophagy is crucial for controlling the manifestation of tuberculosis. This study intends to discover autophagy-related molecular clusters as biomarkers for discriminating between latent tuberculosis (LTBI) and active tuberculosis (ATB) in children through gene expression profile analysis.

METHODS

The expression of autophagy modulators was examined in pediatric patients with LTBI and ATB utilizing public datasets from the Gene Expression Omnibus (GEO) collection (GSE39939 and GSE39940).

RESULTS

In a training dataset (GSE39939), patients with LTBI and ATB exhibited the expression of autophagy-related genes connected with their active immune responses. Two molecular clusters associated with autophagy were identified. Compared to Cluster 1, Cluster 2 was distinguished through decreased adaptive cellular immune response and enhanced inflammatory activation, according to single-sample gene set enrichment analysis (ssGSEA). Per the study of gene set variation, Cluster 2's differentially expressed genes (DEGs) played a role in synthesizing transfer RNA, DNA repair and recombination, and primary immunodeficiency. The peak variation efficiency, root mean square error, and area under the curve (AUC) (AUC = 0.950) were all lowered in random forest models. Finally, a seven-gene-dependent random forest profile was created utilizing the CD247, MAN1C1, FAM84B, HSZFP36, SLC16A10, DTX3, and SIRT4 genes, which performed well against the validation dataset GSE139940 (AUC = 0.888). The nomogram calibration and decision curves performed well in identifying ATB from LTBI.

CONCLUSIONS

In summary, according to the present investigation, autophagy and the immunopathology of TB might be correlated. Furthermore, this investigation established a compelling prediction expression profile for measuring autophagy subtype development risks, which might be employed as possible biomarkers in children to differentiate ATB from LTBI.

Salidroside prevents gestational hypertension-induced impairment of offspring learning and memory via Wnt/Skp2 pathway

BACKGROUND

Salidroside (Sal) has been found to protect against multiple impairments caused by diabetes, and we designed this study to investigate the effect of Sal on gestational hypertension (GHP)-induced impairment of offspring learning and memory.

METHODS

We established a GHP rat model by intraperitoneal injection of NG-nitro-L-arginine methyl ester (L-NAME), and treated with Sal by daily gavage. We used Morris Water Maze test to evaluate the learning and memory ability of offspring rats. HE staining was used to measured the pathological changes in hippocampus of offspring. Immunohistochemistry, cellular immunofluorescence and western blot were used to detect the protein expression.

RESULTS

The learning and memory abilities of GHP offspring rats were significantly lower than those of normal rat offspring, while Sal treatment could significantly improve the learning and memory abilities of GHP offspring rats. HE staining did not reveal pathological differences in the hippocampus of normal rats, GHP rats and Sal-treated GHP offspring rats. However, Sal treatment can significantly increase the expression of Wnt1 and Skp2 protein, and decrease the expression of P27kiwf and P21waf1 protein in the hippocampus of GHP offspring rats. In vitro, Sal significantly promoted the proliferation and differentiation on neural stem cell, while Wnt1 knockdown could reverse these promotions by Sal. In the hippocampus of GHP offspring rats, Sal treatment significantly increased the expression of Tuj1, SOX2, Ki67 and DCX protein.

CONCLUSION

Salidroside significantly improves the learning and memory impairment of offspring caused by GHP, and its mechanism may be related to the fact that Salidroside promotes the proliferation and differentiation of neural stem cells by activating the Wnt1/Skp2 signaling pathway.

Efferocytosis by macrophages in physiological and pathological conditions: regulatory pathways and molecular mechanisms

Efferocytosis is defined as the highly effective phagocytic removal of apoptotic cells (ACs) by professional or non-professional phagocytes. Tissue-resident professional phagocytes ("efferocytes"), such as macrophages, have high phagocytic capacity and are crucial to resolve inflammation and aid in homeostasis. Recently, numerous exciting discoveries have revealed divergent (and even diametrically opposite) findings regarding metabolic immune reprogramming associated with efferocytosis by macrophages. In this review, we highlight the key metabolites involved in the three phases of efferocytosis and immune reprogramming of macrophages under physiological and pathological conditions. The next decade is expected to yield further breakthroughs in the regulatory pathways and molecular mechanisms connecting immunological outcomes to metabolic cues as well as avenues for "personalized" therapeutic intervention.

The role and therapeutic potential of SIRTs in sepsis

Sepsis is a life-threatening organ dysfunction caused by the host's dysfunctional response to infection. Abnormal activation of the immune system and disturbance of energy metabolism play a key role in the development of sepsis. In recent years, the Sirtuins (SIRTs) family has been found to play an important role in the pathogenesis of sepsis. SIRTs, as a class of histone deacetylases (HDACs), are widely involved in cellular inflammation regulation, energy metabolism and oxidative stress. The effects of SIRTs on immune cells are mainly reflected in the regulation of inflammatory pathways. This regulation helps balance the inflammatory response and may lessen cell damage and organ dysfunction in sepsis. In terms of energy metabolism, SIRTs can play a role in immunophenotypic transformation by regulating cell metabolism, improve mitochondrial function, increase energy production, and maintain cell energy balance. SIRTs also regulate the production of reactive oxygen species (ROS), protecting cells from oxidative stress damage by activating antioxidant defense pathways and maintaining a balance between oxidants and reducing agents. Current studies have shown that several potential drugs, such as Resveratrol and melatonin, can enhance the activity of SIRT. It can help to reduce inflammatory response, improve energy metabolism and reduce oxidative stress, showing potential clinical application prospects for the treatment of sepsis. This review focuses on the regulation of SIRT on inflammatory response, energy metabolism and oxidative stress of immune cells, as well as its important influence on multiple organ dysfunction in sepsis, and discusses and summarizes the effects of related drugs and compounds on reducing multiple organ damage in sepsis through the pathway involving SIRTs. SIRTs may become a new target for the treatment of sepsis and its resulting organ dysfunction, providing new ideas and possibilities for the treatment of this life-threatening disease.

Sirtuins in macrophage immune metabolism: A novel target for cardiovascular disorders

Sirtuins (SIRT1-SIRT7), as a family of NAD+-dependent protein modifying enzymes, have various catalytic functions, such as deacetylases, dealkalylases, and deribonucleases. The Sirtuins family is directly or indirectly involved in pathophysiological processes such as glucolipid metabolism, oxidative stress, DNA repair and inflammatory response through various pathways and assumes an important role in several cardiovascular diseases such as atherosclerosis, myocardial infarction, hypertension and heart failure. A growing number of studies supports that metabolic and bioenergetic reprogramming directs the sequential process of inflammation. Failure of homeostatic restoration leads to many inflammatory diseases, and that macrophages are the central cells involving the inflammatory response and are the main source of inflammatory cytokines. Regulation of cellular metabolism has emerged as a fundamental process controlling macrophage function, but its exact signaling mechanisms remain to be revealed. Understanding the precise molecular basis of metabolic control of macrophage inflammatory processes may provide new approaches for targeting immune metabolism and inflammation. Here, we provide an update of studies in cardiovascular disease on the function and role of sirtuins in macrophage inflammation and metabolism, as well as drug candidates that may interfere with sirtuins, pointing to future prospects in this field.

LncRNA NEAT1/miR-211/IL-10 Axis Regulates Inflammation of Peripheral Blood Mononuclear Cells in Acute Myocardial Infarction

This study aimed to explore the expression of long non-coding RNA (lncRNA) nuclear paraspeckle assembly transcript 1 (NEAT1) in patients with acute myocardial infarction (AMI) and its inflammatory regulation mechanism through miR-211/interleukin 10 (IL-10) axis.A total of 75 participants were enrolled in this study: 25 healthy people in the control group, 25 patients with stable angina pectoris (SAP) in the SAP group, and 25 patients with AMI in the AMI group. Real-time qPCR was used to detect mRNA expression levels of NEAT1, miR-211, and IL-10. The interaction between miR-211, NEAT1, and IL-10 was confirmed by dual-luciferase reporter assay, and protein expression was detected using western blot.High expression of NEAT1 in peripheral blood mononuclear cells (PBMCs) of patients with AMI was negatively related to serum creatine kinase-MB (CK-MB), cardiac troponin I (cTnI), tumor necrosis factor-α (TNF-α), IL-6, and IL-1β and was positively correlated with left ventricular ejection fraction (LVEF). In THP-1 cells, miR-211 was confirmed to target and inhibit IL-10 expression. NEAT1 knockdown and miR-211-mimic markedly decreased IL-10 protein levels, whereas anti-miR-211 markedly increased IL-10 protein levels. Importantly, miR-211 level was negatively related to NEAT1 and IL-10 levels, whereas IL-10 level was positively related to the level of NEAT1 expression in PBMCs of patients with AMI.LncRNA NEAT1 was highly expressed in PBMCs of patients with AMI, and NEAT1 suppressed inflammation via miR-211/IL-10 axis in PBMCs of patients with AMI.

MiR-15b-5p and PCSK9 inhibition reduces lipopolysaccharide-induced endothelial dysfunction by targeting SIRT4

BACKGROUND

Endothelial dysfunction and deregulated microRNAs (miRNAs) participate in the development of sepsis and are associated with septic organ failure and death. Here, we explored the role of miR-15b-5p on inflammatory pathways in lipopolysaccharide (LPS)-treated human endothelial cells, HUVEC and TeloHAEC.

METHODS

The miR-15b-5p levels were evaluated in LPS-stimulated HUVEC and TeloHAEC cells by quantitative real-time PCR (qRT-PCR). Functional experiments using cell counting kit-8 (CCK-8), transfection with antagomir, and enzyme-linked immunosorbent assays (ELISA) were conducted, along with investigation of pyroptosis, apoptosis, autophagy, and mitochondrial reactive oxygen species (ROS) by cytofluorometric analysis and verified by fluorescence microscopy. Sirtuin 4 (SIRT4) levels were detected by ELISA and immunoblotting, while proprotein convertase subtilisin-kexin type 9 (PCSK9) expression was determined by flow cytometry (FACS) and immunofluorescence analyses. Dual-luciferase reporter evaluation was performed to confirm the miR-15b-5p-SIRT4 interaction.

RESULTS

The results showed a correlation among miR-15b-5p, PCSK9, and SIRT4 levels in septic HUVEC and TeloHAEC. Inhibition of miR-15b-5p upregulated SIRT4 content, alleviated sepsis-related inflammatory pathways, attenuated mitochondrial stress, and prevented apoptosis, pyroptosis, and autophagic mechanisms. Finally, a PCSK9 inhibitor (i-PCSK9) was used to analyze the involvement of PCSK9 in septic endothelial injury. i-PCSK9 treatment increased SIRT4 protein levels, opposed the septic inflammatory cascade leading to pyroptosis and autophagy, and strengthened the protective role of miR-15b-5p inhibition. Increased luciferase signal validated the miR-15b-5p-SIRT4 binding.

CONCLUSIONS

Our in vitro findings suggested the miR-15b-5p-SIRT4 axis as a suitable target for LPS-induced inflammatory pathways occurring in sepsis, and provide additional knowledge on the beneficial effect of i-PCSK9 in preventing vascular damage by targeting SIRT4.

Multiplex Analysis of Cytokines and Chemokines in Persons Aging With or Without HIV

People with HIV (PWH) on combination antiretroviral therapy (cART) are living longer lives due to modern cART advances and increased routine medical care. The full landscape of aging with HIV is unclear; given that HIV emerged relatively recently in human history and initially had a high mortality rate, there has not been a substantially aged population to evaluate. In this study, we set out to perform high-throughput plasma analyte profiling by multiplex analysis, focusing on various T helper (Th)-related cytokines, chemokines, and proinflammatory and anti-inflammatory cytokines. The primary goals being to provide reference ranges of these analytes for aging PWH cohorts, as well as testing the utility of high-throughput multiplex plasma assays. The cohort used in this study comprised age-matched healthy donors (32.6-73.5 years of age), PWH on cART (26.7-60.2 years of age), and viremic PWH (27.5-59.4 years of age). The patients in each group were then stratified across the age span to examine age-related impacts of these plasma biomarkers. Our results largely indicate feasibility of plasma analyte monitoring by multiplex and demonstrate a high degree of person-to-person variability regardless of age and HIV status. Nonetheless, we find multiple associations with age, duration of known infection, and viral load, all of which appear to be driven by either prolonged HIV disease progression or long-term use of cART.

Sirtuin-dependent metabolic and epigenetic regulation of macrophages during tuberculosis

Macrophages are the preeminent phagocytic cells which control multiple infections. Tuberculosis a leading cause of death in mankind and the causative organism Mycobacterium tuberculosis (MTB) infects and persists in macrophages. Macrophages use reactive oxygen and nitrogen species (ROS/RNS) and autophagy to kill and degrade microbes including MTB. Glucose metabolism regulates the macrophage-mediated antimicrobial mechanisms. Whereas glucose is essential for the growth of cells in immune cells, glucose metabolism and its downsteam metabolic pathways generate key mediators which are essential co-substrates for post-translational modifications of histone proteins, which in turn, epigenetically regulate gene expression. Herein, we describe the role of sirtuins which are NAD+-dependent histone histone/protein deacetylases during the epigenetic regulation of autophagy, the production of ROS/RNS, acetyl-CoA, NAD+, and S-adenosine methionine (SAM), and illustrate the cross-talk between immunometabolism and epigenetics on macrophage activation. We highlight sirtuins as emerging therapeutic targets for modifying immunometabolism to alter macrophage phenotype and antimicrobial function.

Metabolic Reprogramming and Its Regulatory Mechanism in Sepsis-Mediated Inflammation

Sepsis is a systemic inflammatory disease caused by an infection that can lead to multiple organ failure. Sepsis alters energy metabolism, leading to metabolic reprogramming of immune cells, which consequently disrupts innate and adaptive immune responses, triggering hyperinflammation and immunosuppression. This review summarizes metabolic reprogramming and its regulatory mechanism in sepsis-induced hyperinflammation and immunosuppression, highlights the significance and intricacies of immune cell metabolic reprogramming, and emphasizes the pivotal role of mitochondria in metabolic regulation and treatment of sepsis. This review provides an up-to-date overview of the relevant literature to inform future research directions in understanding the regulation of sepsis immunometabolism. Metabolic reprogramming has great promise as a new target for sepsis treatment in the future.

The helminth derived peptide FhHDM-1 redirects macrophage metabolism towards glutaminolysis to regulate the pro-inflammatory response

We have previously identified an immune modulating peptide, termed FhHDM-1, within the secretions of the liver fluke, Fasciola hepatica, which is sufficiently potent to prevent the progression of type 1 diabetes and multiple sclerosis in murine models of disease. Here, we have determined that the FhHDM-1 peptide regulates inflammation by reprogramming macrophage metabolism. Specifically, FhHDM-1 switched macrophage metabolism to a dependence on oxidative phosphorylation fuelled by fatty acids and supported by the induction of glutaminolysis. The catabolism of glutamine also resulted in an accumulation of alpha ketoglutarate (α-KG). These changes in metabolic activity were associated with a concomitant reduction in glycolytic flux, and the subsequent decrease in TNF and IL-6 production at the protein level. Interestingly, FhHDM-1 treated macrophages did not express the characteristic genes of an M2 phenotype, thereby indicating the specific regulation of inflammation, as opposed to the induction of an anti-inflammatory phenotype per se. Use of an inactive derivative of FhHDM-1, which did not modulate macrophage responses, revealed that the regulation of immune responses was dependent on the ability of FhHDM-1 to modulate lysosomal pH. These results identify a novel functional association between the lysosome and mitochondrial metabolism in macrophages, and further highlight the significant therapeutic potential of FhHDM-1 to prevent inflammation.

Sepsis, pyruvate, and mitochondria energy supply chain shortage

Balancing high energy-consuming danger resistance and low energy supply of disease tolerance is a universal survival principle that often fails during sepsis. Our research supports the concept that sepsis phosphorylates and deactivates mitochondrial pyruvate dehydrogenase complex control over the tricarboxylic cycle and the electron transport chain. StimulatIng mitochondrial energetics in septic mice and human sepsis cell models can be achieved by inhibiting pyruvate dehydrogenase kinases with the pyruvate structural analog dichloroacetate. Stimulating the pyruvate dehydrogenase complex by dichloroacetate reverses a disruption in the tricarboxylic cycle that induces itaconate, a key mediator of the disease tolerance pathway. Dichloroacetate treatment increases mitochondrial respiration and ATP synthesis, decreases oxidant stress, overcomes metabolic paralysis, regenerates tissue, organ, and innate and adaptive immune cells, and doubles the survival rate in a murine model of sepsis.

Exploring the role of macrophages in determining the pathogenesis of liver fluke infection

The food-borne trematodes, Opisthorchis viverrini and Clonorchis sinensis, are classified as group 1 biological carcinogens: definitive causes of cancer. By contrast, infections with Fasciola hepatica, also a food-borne trematode of the phylum Platyhelminthes, are not carcinogenic. This review explores the premise that the differential activation of macrophages during infection with these food-borne trematodes is a major determinant of the pathological outcome of infection. Like most helminths, the latter stages of infection with all 3 flukes induce M2 macrophages, a phenotype that mediates the functional repair of tissue damaged by the feeding and migratory activities of the parasites. However, there is a critical difference in how the development of pro-inflammatory M1 macrophages is regulated during infection with these parasites. While the activation of the M1 macrophage phenotype is largely suppressed during the early stages of infection with F. hepatica, M1 macrophages predominate in the bile ducts following infection with O. viverrini and C. sinensis. The anti-microbial factors released by M1 macrophages create an environment conducive to mutagenesis, and hence the initiation of tumour formation. Subsequently, the tissue remodelling processes induced by the M2 macrophages promote the proliferation of mutated cells, and the expansion of cancerous tissue. This review will also explore the interactions between macrophages and parasite-derived signals, and their contributions to the stark differences in the innate immune responses to infection with these parasites.

PDIA2 Bridges Endoplasmic Reticulum Stress and Metabolic Reprogramming During Malignant Transformation of Chronic Colitis

Background

Chronic inflammation contributes to approximately 20% of cancers; the underlying mechanisms are still elusive. Here, using an animal model of colitis to colon-cancerous transformation, we demonstrated that endoplasmic reticulum (ER) stress couples with metabolic reprogramming to promote a malignant transformation of chronic inflammation.

Methods

The animal model for chronic colitis to colon-cancerous transformation was established in C57BL/6N mice by azoxymethane (AOM) and dextran sodium sulfate (DSS) treatments. The differential proteins in control and AOM/DSS-treated colon mucosa were determined using proteomic analysis; the kinetics of metabolic modifications were monitored by mitochondrial oxygen flux, extracellular acidification, and targeted metabolomics; the molecule linker between ER stress and metabolic modifications were identified by coimmunoprecipitation, KEGG pathway analysis, and the subcutaneous tumor model using gene-specific knockdown colon cancer cells. Tissue array analysis were used to evaluate the differential protein in cancer and cancer-adjacent tissues.

Results

AOM/DSS treatment induced 38 tumors in 10 mice at the 14th week with the mean tumor size 9.35 ± 3.87 mm², which was significantly decreased to 5.85 ± 0.95 mm² by the ER stress inhibitor 4-phenylbutyric acid (4PBA). Seven differential proteins were determined from control (1,067 ± 48) and AOM/DSS-treated mucosa (1,077 ± 59); the level of ER protein PDIA2 (protein disulfide isomerase-associated 2) was increased over 7-fold in response to AOM/DSS treatment. PDIA2 interacted with 420 proteins that were involved in 8 signaling pathways, in particular with 53 proteins in metabolic pathways. PDIA2 translocated from ER to mitochondria and interacted with the components of complexes I and II to inhibit oxophosphorylation but increase glycolysis. Knockdown PDIA2 in colon cancer cells restored the metabolic imbalance and significantly repressed tumor growth in the xenograft animal model. 4PBA therapy inhibited the AOM/DSS-mediated overexpression of PDIA2 and metabolic modifications and suppressed colon cancer growth. In clinic, PDIA2 was overexpressed in colon cancer tissues rather than cancer-adjacent tissues and was related with the late stages and lymph node metastasis of colon cancer.

Conclusions

Persistent ER stress reprograms the metabolism to promote the malignant transformation of chronic colitis; PDIA2 serves as a molecule linker between ER stress and metabolic reprogramming. The inhibition of ER stress restores metabolic homeostasis and attenuates the cancerous transformation of chronic inflammation.

Sirtuins are crucial regulators of T cell metabolism and functions

It is well known that metabolism underlies T cell differentiation and functions. The pathways regulating T cell metabolism and function are interconnected, and changes in T cell metabolic activity directly impact the effector functions and fate of T cells. Thus, understanding how metabolic pathways influence immune responses and ultimately affect disease progression is paramount. Epigenetic and posttranslational modification mechanisms have been found to control immune responses and metabolic reprogramming. Sirtuins are NAD⁺-dependent histone deacetylases that play key roles during cellular responses to a variety of stresses and have recently been reported to have potential roles in immune responses. Therefore, sirtuins are of significant interest as therapeutic targets to treat immune-related diseases and enhance antitumor immunity. This review aims to illustrate the potential roles of sirtuins in different subtypes of T cells during the adaptive immune response.

Sirtuins, enzymes that regulate how cells respond to stress, regulate T cell metabolism and functions, and therefore blocking or boosting sirtuins influences immune responses. As part of the immune system, some types of T cells attack specific targets; others keep the immune response in check. Imene Hamaidi and Sungjune Kim at H. Lee Moffitt Cancer Center, Tampa, USA, have reviewed how sirtuins affect different subsets of T cells to either promote or suppress immune responses. Boosting sirtuins that increase the function of inflammation-suppressing T cells can improve outcomes for transplant recipients or help treat autoimmune diseases. Conversely, stimulating immune-activating sirtuins can help re-energize exhausted antitumor T cells. Understanding the complex web of sirtuin–T cell interactions may help in developing therapeutic strategies for improving transplant outcomes, and for treating autoimmune diseases and cancer.

Long non‑coding RNA TUG1 sponges microRNA‑9 to protect podocytes from high glucose‑induced apoptosis and mitochondrial dysfunction via SIRT1 upregulation

Podocyte apoptosis and mitochondrial dysfunction serve a major role in diabetic nephropathy progression. The present study revealed a molecular mechanism regulating podocyte apoptosis and mitochondrial dysfunction. In vitro models were established using conditionally immortalized mouse podocyte clonal cells treated with high glucose (HG). Reverse quantitative-transcription PCR were used to detect gene expression, western blotting and immunofluorescence were used to detect protein expression, Cell Counting Kit-8 was used to detect cell viability and flow cytometry was used to detect cell apoptosis. HG treatment in the mouse podocyte clonal cells downregulated taurine-upregulated gene 1 (TUG1) expression and decreased viability in a dose-dependent manner. In addition, TUG1 knockdown (KD) increased HG-induced apoptosis, while TUG1 overexpression (OE) reduced HG-induced apoptosis in podocytes. HG-induced mitochondrial dysfunction was identified in podocytes, with increased reactive oxygen species levels, decreased complex I/III activity and decreased basal/maximal oxygen consumption rate. TUG1 KD worsened HG-induced mitochondrial dysfunction, and TUG1 OE reversed these effects. At the molecular level, TUG1 was revealed to promote sirtuin 1 (SIRT1) expression by sponging microRNA (miR)-9, and SIRT1 OE reversed the HG-induced apoptosis and mitochondrial dysfunction increased by TUG1 KD. The present data indicated that downregulation of TUG1 induced by HG was associated with HG-induced apoptosis and mitochondrial dysfunction in podocytes, and that TUG1 protected HG-induced podocytes by promoting SIRT1 expression via miR-9 inhibition.

Paeoniflorin Enhances the Sensitivity of ER-Positive Breast Cancer Cells to Tamoxifen through Promoting Sirtuin 4

Tamoxifen is an effective drug for treating patients with advanced estrogen receptor-positive (ER+) breast cancer (BC), but not for all ER + BC patients. Drug tolerance is the biggest obstacle. In this study, we designed an experiment to investigate whether paeoniflorin affects the ER + BC cell's sensitivity to tamoxifen in the T47D and MCF-7 cell lines. Herein, we found that paeoniflorin inhibited cell proliferation without inducing apoptosis. However, it enhanced tamoxifen-induced apoptosis in both cell lines. Immunoblotting revealed that paeoniflorin significantly increased the already elevated Bax/Bcl2 protein expression ratio and the caspase 3 activity levels, both induced by tamoxifen. Paeoniflorin was also found to increase SIRT4 expression, and deletion of SIRT4 could significantly reverse the inhibition of cell proliferation induced by paeoniflorin and significantly decrease paeoniflorin-enhanced apoptosis induced by tamoxifen. Moreover, protein expression detection revealed that paeoniflorin enhanced the tamoxifen-induced inhibition of STAT3 activation. Besides, the deletion of SIRT4 could significantly increase STAT3 activation in the T47D and MCF-7 cells. In conclusion, paeoniflorin suppressed STAT3 activation to enhance the sensitivity of ER-positive breast cancer cells to tamoxifen through promoting SIRT4 expression.

Sirtuins and Sepsis: Cross Talk between Redox and Epigenetic Pathways

Sepsis and septic shock are the leading causes of death among hospitalized patients in the US. The immune response in sepsis transitions from a pro-inflammatory and pro-oxidant hyper-inflammation to an anti-inflammatory and cytoprotective hypo-inflammatory phase. While 1/3rd sepsis-related deaths occur during hyper-, a vast majority of sepsis-mortality occurs during the hypo-inflammation. Hyper-inflammation is cytotoxic for the immune cells and cannot be sustained. As a compensatory mechanism, the immune cells transition from cytotoxic hyper-inflammation to a cytoprotective hypo-inflammation with anti-inflammatory/immunosuppressive phase. However, the hypo-inflammation is associated with an inability to clear invading pathogens, leaving the host susceptible to secondary infections. Thus, the maladaptive immune response leads to a marked departure from homeostasis during sepsis-phases. The transition from hyper- to hypo-inflammation occurs via epigenetic programming. Sirtuins, a highly conserved family of histone deacetylators and guardians of homeostasis, are integral to the epigenetic programming in sepsis. Through their anti-inflammatory and anti-oxidant properties, the sirtuins modulate the immune response in sepsis. We review the role of sirtuins in orchestrating the interplay between the oxidative stress and epigenetic programming during sepsis.

Carbon Nanotubes Promote the Development of Intestinal Organoids through Regulating Extracellular Matrix Viscoelasticity and Intracellular Energy Metabolism

The biological effect of engineered carbon nanotubes (CNTs) as beneficial biomaterials on the intestine, especially on its development, remains unclear. Here, we investigated the profitable effect of CNTs with a different graphene layer and surface modification on the 3D model of intestinal organoids and demonstrated that CNTs (50 μg/mL) promoted the development of intestinal organoids over time (0-5 days). The mechanisms involve the modulation of extracellular matrix (ECM) viscoelasticity and intracellular energy metabolism. In particular, CNTs reduced the hardness of the extracellular matrix through decreasing the elasticity and increasing the viscosity as a result of elevated metalloproteinase and binding to a protein scaffold, which activated the mechanical membrane sensors of cells, Piezo, and downstream P-p38-yes-associated protein (YAP) pathway. Moreover, CNTs altered the metabolic profile of intestinal organoids and induced increased mitochondria activity, respiration, and nutrient absorption. These mechanisms cooperated with each other to promote the proliferation and differentiation of intestinal organoids. In addition, the promoted effect of CNTs is highly dependent on the number of graphene layers, manifested as multiwalled CNTs > single-walled CNTs. Our findings highlight the CNT-intestine interaction and imply the potential of CNTs as biomaterials for intestine-associated tissue engineering.

LncRNA OIP5-AS1 Regulates the Warburg Effect Through miR-124-5p/IDH2/HIF-1α Pathway in Cervical Cancer

Hypoxia reprogrammed glucose metabolism affects the Warburg effect of tumor cells, but the mechanism is still unclear. Long-chain non-coding RNA (lncRNA) has been found by many studies to be involved in the Warburg effect of tumor cells under hypoxic condition. Herein, we find that lncRNA OIP5-AS1 is up-regulated in cervical cancer tissues and predicts poor 5-years overall survival in cervical cancer patients, and it promotes cell proliferation of cervical cancer cells in vitro and in vivo. Moreover, OIP5-AS1 is a hypoxia-responsive lncRNA and is essential for hypoxia-enhanced glycolysis which is IDH2 or hypoxia inducible factor-1α (HIF-1α) dependent. In cervical cancer cells, OIP5-AS1 promotes IDH2 expression by inhibiting miR-124-5p, and IDH2 promotes the Warburg effect of cervical under hypoxic condition through regulating HIF-1α expression. In conclusion, hypoxia induced OIP5-AS1 promotes the Warburg effect through miR-124-5p/IDH2/HIF-1α pathway in cervical cancer.

Role of Histone Deacetylases in Monocyte Function in Health and Chronic Inflammatory Diseases

Histone deacetylases (HDACs) are a family of 18 members that participate in the epigenetic regulation of gene expression. In addition to histones, some HDACs also deacetylate transcription factors and specific cytoplasmic proteins.Monocytes, as part of the innate immune system, maintain tissue homeostasis and help fight infections and cancer. In these cells, HDACs are involved in multiple processes including proliferation, migration, differentiation, inflammatory response, infections, and tumorigenesis. Here, a systematic description of the role that most HDACs play in these functions is reviewed. Specifically, some HDACs induce a pro-inflammatory response and play major roles in host defense. Conversely, other HDACs reprogram monocytes and macrophages towards an immunosuppressive phenotype. The right balance between both types helps monocytes to respond correctly to the different physiological/pathological stimuli. However, aberrant expressions or activities of specific HDACs are associated with autoimmune diseases along with other chronic inflammatory diseases, infections, or cancer.This paper critically reviews the interesting and extensive knowledge regarding the role of some HDACs in these pathologies. It also shows that as yet, very little progress has been made toward the goal of finding effective HDAC-targeted therapies. However, given their obvious potential, we conclude that it is worth the effort to develop monocyte-specific drugs that selectively target HDAC subtypes with the aim of finding effective treatments for diseases in which our innate immune system is involved.

Mitochondrial Dysfunction is Associated With an Immune Paralysis Phenotype in Pediatric Sepsis

OBJECTIVE

Immune dysregulation is a defining feature of sepsis, but the role for mitochondria in the development of immunoparalysis in pediatric sepsis is not known. We sought to determine if mitochondrial dysfunction measured in peripheral blood mononuclear cells (PBMCs) is associated with immunoparalysis and systemic inflammation in children with sepsis.

DESIGN

Prospective observational study.

SETTING

Single-academic pediatric intensive care unit (PICU).

PATIENTS

One hundred sixty-one children with sepsis/septic shock and 18 noninfected PICU controls.

MEASUREMENTS AND MAIN RESULTS

Mitochondrial respiration in PBMCs, markers of immune function, and plasma cytokines were measured on days 1 to 2 (T1), 3 to 5 (T2), and 8 to 14 (T3) after sepsis recognition, and once for controls. Immunoparalysis was defined as whole-blood ex vivo lipopolysaccharide-induced tumor necrosis factor-alpha (TNF-α) ≤200 pg/mL or monocyte human leukocyte antigen-DR ≤30%. Mitochondrial respiration was lower in children with versus without immunoparalysis measured at the same timepoint. Mitochondrial respiration measured early (at T1 and T2) was also lower in those with immunoparalysis at T2 and T3, respectively. Although most patients with immunoparalysis exhibited low mitochondrial respiration, this metabolic finding was not specific to the immunoparalysis phenotype. Plasma cytokines, including IL-8, IL-10, TNF-α, and MCP-1, were highest in the subset of sepsis patients with immune paralysis or low mitochondrial respiration at T1.

CONCLUSIONS

Children with sepsis had lower PBMC mitochondrial respiration when immunoparalysis was present compared with those without immunoparalysis. The subsets with immune paralysis and low mitochondrial respiration exhibited the highest levels of systemic inflammation.

Genistein Attenuates Isoflurane-Induced Neuroinflammation by Inhibiting TLR4-Mediated Microglial-Polarization in vivo and in vitro

Background

Isoflurane, a widely used anesthetic in surgery, has been found to induce neurotoxicity. In parallel, genistein is thought to attenuate isoflurane-induced neurotoxicity, although underlying molecular mechanisms are still unclear. In this study, we studied the protective effects of genistein on isoflurane-induced neuroinflammation in rats and BV2 cells.

Methods

Sprague-Dawley rat pups were exposed to 0.75% isoflurane for 6 hours at postnatal day 7 (P7), and genistein (20, 40, or 80 mg/kg/day) or saline administered from P3 to P15. Hippocampal single-cell suspensions were prepared and apoptosis analyzed by flow cytometry. mRNA expression was determined by RT-qPCR, while protein expression was assessed using Western blot, immunochemistry and immunofluorescence. TLR4 was knocked-out in BV2 cells through CRISPR-Cas9.

Results

Genistein treatment reduced isoflurane-induced apoptosis and inflammation in rat hippocampus. Importantly, genistein promoted M2 and suppressed M1 microglia polarization in rat hippocampus after stimulation with isoflurane. In addition, genistein reduced isoflurane-induced protein expression levels of TLR4, MyD88, TRAF6, p-TAK1, p-p38, p-ERK, p-IκBα and p-NF-κB in rat hippocampus. In BV2 cells exposed to isoflurane, genistein treatment decreased IL-1β, TNF-α, IL-6 and IL-8 mRNA expressions, promoted M2 and suppressed M1 microglia polarization. Similarly, genistein also decreased TLR4 protein levels in isoflurane-induced BV2 cells. However, genistein did not affect CD16, iNOS, CD206 and Arg1 protein levels in TLR4-KO BV2 cells exposed to isoflurane.

Conclusion

Genistein attenuates isoflurane-induced neurotoxicity by inhibiting TLR4-mediated microglial inflammation in vivo and in vitro.

Energy metabolism disorders and potential therapeutic drugs in heart failure

Heart failure (HF) is a global public health problem with high morbidity and mortality. A large number of studies have shown that HF is caused by severe energy metabolism disorders, which result in an insufficient heart energy supply. This deficiency causes cardiac pump dysfunction and systemic energy metabolism failure, which determine the development of HF and recovery of heart. Current HF therapy acts by reducing heart rate and cardiac preload and afterload, treating the HF symptomatically or delaying development of the disease. Drugs aimed at cardiac energy metabolism have not yet been developed. In this review, we outline the main characteristics of cardiac energy metabolism in healthy hearts, changes in metabolism during HF, and related pathways and targets of energy metabolism. Finally, we discuss drugs that improve cardiac function via energy metabolism to provide new research ideas for the development and application of drugs for treating HF.

Long non-coding RNA HOTAIR promotes the progression of synovial sarcoma through microRNA-126/stromal cell-derived factor-1 regulation

The long non-coding RNA (lncRNA) HOTAIR is an oncogene, that has been reported to be aberrantly expressed in multiple types of malignant tumor tissues. However, its expression and association with synovial sarcoma (SS) remains unclear. The present study aimed to elucidate the expression level of HOTAIR in SS tissues and also identify its role. Reverse transcription-quantitative PCR was used to detect the expression level of HOTAIR and microRNA (miR)-126 in 54 tissue samples from patients with SS, in 10 tissue samples from synovium tissues of normal patients, and in SW982 cells. The protein expression level was measured using western blot analysis and cellular immunofluorescence. Cellular proliferation, invasion and migration were assessed using MTT, Transwell and wound healing assays, respectively. HOTAIR was expressed at high levels in SS tissues. In contrast, miR-126 was expressed at low levels in SS tissues, and was negatively correlated with HOTAIR expression. HOTAIR knockdown in SW982 cells inhibited cellular proliferation in vitro, but also significantly increased the ratio of cells in the G₁/G₀ phase of the cell cycle, and decreased the ratio of cells in the G₂/S phase. In addition, HOTAIR knockdown inhibited the invasion and migration of the SW982 cells, as observed in the Transwell and wound healing assays. Furthermore, HOTAIR knockdown increased miR-126 expression level and decreased the expression level of stromal cell-derived factor-1 (SDF-1) at the protein level. On the other hand, while miR-126-mimic decreased the protein expression level of SDF-1, miR-126-inhibitor increased its expression level in SW982 cells. Notably, HOTAIR knockdown or SDF-1 knockout significantly decreased the protein expression levels of CDK1, CDK2, cyclin D1, MMP-9, vimentin and N-cadherin, and significantly increased the protein expression levels of p21, p53 and E-cadherin in SW982 cells. HOTAIR was highly expressed in SS tissues, wherein it could promote the proliferation, invasion and migration of SS cells by increasing the expression of SDF-1 via miR-126 inhibition.

Macrophages in Chronic Liver Failure: Diversity, Plasticity and Therapeutic Targeting

Chronic liver injury results in immune-driven progressive fibrosis, with risk of cirrhosis development and impact on morbidity and mortality. Persistent liver cell damage and death causes immune cell activation and inflammation. Patients with advanced cirrhosis additionally experience pathological bacterial translocation, exposure to microbial products and chronic engagement of the immune system. Bacterial infections have a high incidence in cirrhosis, with spontaneous bacterial peritonitis being the most common, while the subsequent systemic inflammation, organ failure and immune dysregulation increase the mortality risk. Tissue-resident and recruited macrophages play a central part in the development of inflammation and fibrosis progression. In the liver, adipose tissue, peritoneum and intestines, diverse macrophage populations exhibit great phenotypic and functional plasticity determined by their ontogeny, epigenetic programming and local microenvironment. These changes can, at different times, promote or ameliorate disease states and therefore represent potential targets for macrophage-directed therapies. In this review, we discuss the evidence for macrophage phenotypic and functional alterations in tissue compartments during the development and progression of chronic liver failure in different aetiologies and highlight the potential of macrophage modulation as a therapeutic strategy for liver disease.

Sirtuin 3 Downregulation in Mycobacterium tuberculosis-Infected Macrophages Reprograms Mitochondrial Metabolism and Promotes Cell Death

Tuberculosis, the disease caused by the bacterium M. tuberculosis, remains one of the top 10 causes of death worldwide. Macrophages, the first cells to encounter M. tuberculosis and critical for defense against infection, are hijacked by M. tuberculosis as a protected growth niche. M. tuberculosis-infected macrophages undergo metabolic reprogramming where key mitochondrial pathways are modulated, but the mechanisms driving this metabolic shift is unknown.

Mycobacterium tuberculosis induces metabolic reprogramming in macrophages like the Warburg effect. This enhances antimicrobial performance at the expense of increased inflammation, which may promote a pathogen-permissive host environment. Since the NAD⁺-dependent protein deacetylase Sirtuin 3 (SIRT3) is an important regulator of mitochondrial metabolism and cellular redox homeostasis, we hypothesized that SIRT3 modulation mediates M. tuberculosis-induced metabolic reprogramming. Infection of immortalized and primary murine macrophages resulted in reduced levels of SIRT3 mRNA and protein and perturbation of SIRT3-regulated enzymes in the tricarboxylic acid cycle, electron transport chain, and glycolytic pathway. These changes were associated with increased reactive oxygen species and reduced antioxidant scavenging, thereby triggering mitochondrial stress and macrophage cell death. Relevance to tuberculosis disease in vivo was indicated by greater bacterial burden and immune pathology in M. tuberculosis-infected Sirt3^−/− mice. CD11b⁺ lung leukocytes isolated from infected Sirt3^−/− mice showed decreased levels of enzymes involved in central mitochondrial metabolic pathways, along with increased reactive oxygen species. Bacterial burden was also greater in lungs of LysM^creSirt3^L2/L2 mice, demonstrating the importance of macrophage-specific SIRT3 after infection. These results support the model of SIRT3 as a major upstream regulatory factor, leading to metabolic reprogramming in macrophages by M. tuberculosis.

Adipose-derived mesenchymal stem cells inhibit cell proliferation and migration and suppress extracellular matrix synthesis in hypertrophic-scar and keloid fibroblasts

Pathological scars occur during skin wound healing, and the use of adipose-derived stem cells (ADSCs) is one of the various treatments. The present study aimed to investigate the in vitro effects of ADSCs on the biological properties of hypertrophic scar fibroblasts (HSFs) and keloid fibroblasts (KFs), such as proliferation, migration, and the synthesis of extracellular matrix proteins. Transwell chambers were used to establish a co-culture system of ADSCs with normal skin fibroblasts (NFs), HSFs or KFs. The effect of ADSCs on the proliferation of fibroblasts was evaluated by CCK8 measurement, while the migration ability of fibroblasts was assessed using cell scratch assay. The expression of extracellular matrix proteins was measured by immunoblotting. Co-culture of NFs with ADSCs did not affect cell proliferation and migration, nor the expression of extracellular matrix proteins [collagen-I, collagen-III, fibronectin (FN) and α-smooth muscle actin (α-SMA)] in NFs. However, as with the inhibitor SB431542, ADSCs significantly inhibited cell proliferation and migration and the expression of extracellular matrix proteins (collagen-I, collagen-III, FN and α-SMA), but also suppressed the protein expression of transforming growth factor β1 (TGF-β1), phosphorylated (p-) mothers against decapentaplegic homolog (Smad) 2, p-Smad3 and Smad7 in HSFs and KFs. The results show that ADSCs inhibited cell proliferation and migration and the expression of extracellular matrix proteins in HSCs and KFs in vitro, possibly through inhibition of the TGF-β1/Smad pathway.

Research Progress of Sirtuin4 in Cancer

Sirtuins (SIRTs) are members of the silent information regulator-2 family. They are a conserved family of nicotinamide adenine dinucleotide-dependent protein lysine deacylases. SIRTS are involved in intricate cellular processes. There are seven subtypes of SIRTs (1–7) in mammals. SIRT4 is located mainly in mitochondria and has various catalytic activities. These enzyme activities give it a diverse range of important biologic functions, such as energy metabolism, oxidative stress, and aging. Cancer is characterized as reprogramming of energy metabolism and redox imbalance, and SIRT4 can affect tumorigenesis. Here, we review the structure, localization, and enzyme activity of SIRT4 and its role in various neoplasms.

The Centrality of Obesity in the Course of Severe COVID-19

The ongoing coronavirus disease 2019 (COVID-19) pandemic caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global public health challenge. Most patients do not experience severe complications, but approximately 25% of patients progress to acute respiratory distress syndrome (ARDS), and the mortality rate is approximately 5-7%. Clinical findings have determined several risk factors for severe complications and mortality in COVID-19 patients, such as advanced age, smoking, obesity, and chronic diseases. Obesity is a common and serious health problem worldwide that initiates a cascade of disorders, including hypertension, cardiovascular disease (CVD), diabetes mellitus, and chronic kidney disease (CKD). The presence of these disorders is linked to a more severe course of COVID-19. Given the "epidemic" of obesity worldwide and the importance of obesity in the progression of COVID-19, we investigated the mechanisms through which obesity increases the susceptibility to and severity of COVID-19 to support the selection of more appropriate therapies for individuals with obesity.

Ginsenoside Rg3 alleviates inflammation in a rat model of myocardial infarction via the SIRT1/NF-κB pathway

Inflammation serves an important role in myocardial infarction (MI). Ginsenoside Rg3 (Rg3), an activator of sirtuin 1 (SIRT1), has been identified to elicit anti-inflammatory effects via the NF-κB pathway. However, the function of Rg3 in MI remains unknown. In the present study, a MI rat model was established by coronary artery ligation and treated with Rg3 to explore whether Rg3 could inhibit inflammation in MI rats by inhibiting the SIRT1/NF-κB pathway. At 28 days post-MI, it was identified that Rg3 not only decreased the ST-segment ECG values in MI rats, but also significantly decreased serum LDH, CK-MB and cTnI levels in MI rats. In addition, Rg3 also significantly decreased serum tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-6 levels and increased serum IL-10 levels in MI rats. In the heart tissues of the MI rats, Rg3 attenuated myocardial pathological changes and cell apoptosis caused by MI, decreased the gene expression levels of TNF-α, IL-1β and IL-6, but increased the gene expression level of IL-10. In addition, the expression levels of the SIRT1 and transcription factor RelB proteins were significantly increased following Rg3 treatment, and the expression level of p-p65/p65 protein was significantly decreased in the heart tissues of MI rats with Rg3 treatment compared with that in heart tissues of MI rats without Rg3 treatment. In conclusion, Rg3 alleviates inflammation in a rat model of MI via the SIRT1/NF-κB pathway.

Gingival fibroblasts dynamically reprogram cellular metabolism during infection of Porphyromonas gingivalis

OBJECTIVE

The purpose of the present study was to explore the sequential changes in the cellular metabolism in gingival fibroblasts (GFs) in response toPorphyromonas gingvalis (P. gingivalis) ATCC33277 infection.

DESIGN

GFs were treated withP. gingivalis at the MOI of 50 for 4, 24 and 48 h to mimic the early, medium, and late phase in the bacterial infection. LDH assay and cell counting kit-8 were utilized to explore cell death and proliferation. Real-time PCR was utilized to explore the gene transcription of pro-inflammatory genes. The relative levels of biomolecules in GFs were measured by gas chromatography-mass spectrometry. Principal component analysis and orthogonal partial least-squares-discriminant analysis were performed to visualize the metabolic difference among experimental groups. In addition, pathway analysis was conducted regarding differential metabolites in GFs.

RESULTS

P. gingivalis infection triggered significant gene transcription of IL-1β, IL 6, MCP 1, and MMP 1 in GFs. In addition, P. gingivalis stimulated cell proliferation of GFs at MOI of 10, 50 and 250. Moreover, P. gingivalis triggered significant cell death at higher MOI. 69, 173 and 148 metabolites were qualitatively detected at 4, 24 and 48 h after P. gingivalis infection respectively in GFs, showing a sequential change of different phase. Kyoto Encyclopedia of Genes and Genomes pathway analysis demonstrated that ATP-binding cassette transporters, glutathione, purine and pyrimidine metabolism was significantly altered in different phase.

CONCLUSIONS

Human GFs may sequentially rewire metabolomics to shape the inflammatory responses and support the proliferation of host cells during P. gingivalis infection.

Hirudin Protects Against Kidney Damage in Streptozotocin-Induced Diabetic Nephropathy Rats by Inhibiting Inflammation via P38 MAPK/NF-κB Pathway

Background

Inflammation-induced podocyte apoptosis plays an important role in kidney injury during diabetic nephropathy (DN). Hirudin (HIR), a natural compound extracted from leeches, can inhibit inflammation. However, whether HIR can protect the kidneys against inflammation during DN is unknown. In the present study, we aimed to study the effects of HIR on kidney damage in a DN rat model and explore its anti-inflammatory properties.

Methods

A streptozotocin-induced DN rat model was generated, and HIR was administered subcutaneously. Immortal podocytes and primary peritoneal macrophages were used for vitro studies. Hematoxylin and eosin staining was used to evaluate renal pathological changes; quantitative polymerase chain reaction and immunoblotting were used to detect gene expression; and TUNEL staining was used to detect apoptotic cells.

Results

Our results showed that HIR protected against renal injury, as indicated by kidney weight/body weight, serum creatinine, renal pathological changes, blood urea nitrogen, and detection of urine proteins. Notably, HIR treatment reduced macrophage infiltration, pro-inflammatory cytokine expression, and podocyte apoptosis in the kidney tissues of DN rats. In vitro, high glucose (HG) induced the activation of M1 macrophages, which was accompanied by increased podocyte apoptosis. HIR could decrease HG-induced podocyte apoptosis and suppress pro-inflammatory cytokine expression in podocytes in vitro. This was achieved via inhibition of p38 MAPK/NF-κB activation in renal tissues and podocytes.

Conclusion

HIR could inhibit inflammation via the p38 MAPK/NF-κB pathway, prevent podocyte apoptosis, and protect against kidney damage in a DN rat model.

Polygonatum sibiricum polysaccharides prevent LPS-induced acute lung injury by inhibiting inflammation via the TLR4/Myd88/NF-κB pathway

Inflammation plays an important role in cases of acute lung injury (ALI), and the Toll-like receptor 4/nuclear factor-κB (TLR4/NF-κB) pathway, which can be regulated by Polygonatum sibiricum polysaccharides (PSPs), is closely related to the dynamics of lipopolysaccharide (LPS)-induced inflammation. Thus, we sought to evaluate whether or not PSPs prevent LPS-induced ALI by way of inhibiting inflammation via the TLR4/NF-κB pathway in rats. We established an ALI rat model by tracheal instillation of LPS, and by pre-injection of PSPs into rats to examine PSPs in the ALI rat model. We found that PSPs attenuated LPS-induced lung pathological changes in ALI rats, decreased LPS-induced myeloperoxidase (MOP) activity, and elevated malondialdehyde (MDA) levels in lung tissue. However, PSPs also decreased the LPS-induced increase in the neutrophil ratio, and decreased inflammatory factor levels in bronchoalveolar lavage fluid (BALF). Moreover, PSPs decreased LPS-induced increases in inflammatory factors measured by mRNA expression, and altered the levels of expression of TLR4, medullary differentiation protein 88 (Myd88), p-IKB-α/IKB-α and p-p65/p65 proteins in lung tissue. In vitro, PSPs also reduced apoptosis induced by LPS in BEAS-2B cells by suppressing inflammation through its effect of inhibiting the TLR4/NF-κB pathway. In conclusion, our results suggest that PSPs may be a potential drug for effective treatment of LPS-induced ALI, due to the ability to inhibit inflammation through effects exerted on the TLR4/Myd88/NF-κB pathway.

miR-9-5p promotes the invasion and migration of endometrial stromal cells in endometriosis patients through the SIRT1/NF-κB pathway

OBJECTIVE

The present study was designed to investigate the expression of miR-9-5p and to study the effect of miR-9-5p expression on the invasion and migration of endometrial stromal cells in endometriosis patients.

METHODS

We recruited 17 eutopic endometrium patients, 19 ectopic endometrium patients, and 13 normal endometrium patients, and we measured their miR-9-5p and SIRT1 expressions. Western blot was used to measure the protein expressions, and cellular immunofluorescence was used to check the positions of the p65 position protein in cells. A Transwell chamber and cell scratch tests were used to test cell invasion and migration, respectively.

RESULTS

miR-9-5p was highly expressed, and SIRT1 was lowly expressed in the endometria of the endometriosis patients, and there was a negative correlation between miR-9-5p and SIRT1 mRNA in the endometriosis patients. A dual luciferase reporter gene system showed that miR-9-5p targeted the inhibition of SIRT1 expression in the endometrial stromal cells. Moreover, the up-regulation of miR-9-5p expression using the miR-9-5p-mimics significantly increased the distance of endometrial stromal cell migration and the number of cells that entered into the lower chamber of the Transwell chamber, and the down-regulation of miR-9-5p using the miR-9-5p-inhibitor significantly decreased the distance of endometrial stromal cell migration and the number of cells that entered into the lower chamber of the Transwell chamber. Moreover, the miR-9-5p-mimics significantly increased the expressions of the P-p65/p65 protein and the 65 protein in the nuclei, and the miR-9-5p-inhibitor significantly decreased the expressions of the P-p65/p65 protein and the 65 protein in the nuclei.

CONCLUSION

miR-9-5p is highly expressed in the endometria of endometriosis patients, and miR-9-5p can promote the invasion and migration of endometrial stromal cells in vitro by targeting the SIRT1 expression via the NF-κB pathway.

Macrophage Immunometabolism and Inflammaging: Roles of Mitochondrial Dysfunction, Cellular Senescence, CD38, and NAD

Aging is a complex process that involves dysfunction on multiple levels, all of which seem to converge on inflammation. Macrophages are intimately involved in initiating and resolving inflammation, and their dysregulation with age is a primary contributor to inflammaging—a state of chronic, low-grade inflammation that develops during aging. Among the age-related changes that occur to macrophages are a heightened state of basal inflammation and diminished or hyperactive inflammatory responses, which seem to be driven by metabolic-dependent epigenetic changes. In this review article we provide a brief overview of mitochondrial functions and age-related changes that occur to macrophages, with an emphasis on how the inflammaging environment, senescence, and NAD decline can affect their metabolism, promote dysregulation, and contribute to inflammaging and age-related pathologies.

Sirtuins: potential therapeutic targets for regulating acute inflammatory response?

Introduction: Sirtuins are highly conserved nicotinamide adenine dinucleotide (NAD+) sensors that are considered the guardians of homeostasis. Acute inflammation, which is intended to ward off pathogen invasion, is nature's highly conserved stress-associated and molecular-based survival mechanism for most life forms. Acute inflammatory responses deviate cells from the homeostasis to enable survival. It is not surprising perhaps, that these two must interact in the most dramatic way to preserve homeostasis and preserve life.Areas covered: In this review, we present an overview of sirtuin responses in acute life-threatening inflammatory conditions. We examine how the seven sirtuins (sirtuins 1-7) are responsible for modulating the acute inflammatory response in a context-dependent manner, thus presenting novel therapeutic targets. The database search includes Medline (since 1966) and PubMed (since 1996).Expert opinion: Sirtuins fine-tune the inflammatory response to acute infectious and noninfectious inflammatory stimuli. Modulating sirtuin activity leads to profound changes in inflammatory response. Sirtuin-activating and inhibiting agents are emerging as therapeutic agents to resolve inflammation and promote homeostasis in chronic inflammation. The use of sirtuin modulation in acute life-threatening inflammatory conditions has great potential.

Denosumab inhibits MCF-7 cell line-induced spontaneous osteoclastogenesis via the RANKL/MALAT1/miR-124 axis

Background

Denosumab is an inhibitor of receptor activator of NF-κB ligand (RANKL), which inhibits bone metastasis (BM) in breast cancer (BC), but does not completely control cancer cell BM in some BC patients. This study was designed to study whether denosumab inhibits human BC cells (MCF-7) cell line-induced spontaneous osteoclastogenesis via RANKL/metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)/miR-124 axis.

Methods

We established a co-culture system of MCF-7-induced spontaneous osteoclastogenesis in RAW 264.7 cells, and denosumab is added into the co-culture system to inhibit RAW 264.7 cell differentiation into osteoclasts. Real-time PCR (RT-PCR), immunofluorescence and western blotting analysis were used to detect gene expression, while tartrate-resistant acid phosphatase (TRAP) staining was used to assess osteoclast formation.

Results

Denosumab inhibits MCF-7 cell line-induced spontaneous osteoclastogenesis, and the inhibition of denosumab was found to be more pronounced after MALAT1 downregulation and miR-124 overexpression. However, MALAT1 knockdown or miR-124 overexpression did not alter RANKL protein expression. Moreover, the dual luciferase gene reporter system showed that miR-124 targeted the inhibition of MALAT1, while si-MALAT1 upregulated miR-124 expression. miR-124-mimics were able to decrease the expression of Rab27a, IL-11, activated T-cell nuclear factor 1 (NFATc1) and TARP protein.

Conclusions

Denosumab inhibits MALAT1 expression by inhibiting RANKL, thereby upregulating miR-124 expression, which ultimately inhibits MCF-7 cell line-induced pseudo osteoclastogenesis.

miR-146a regulates inflammation and development in patients with abdominal aortic aneurysms by targeting CARD10

BACKGROUND

We present the expression of miR-146a in abdominal aortic aneurysms (AAA) patients, and its mechanism for regulating inflammation and development in AAA patients.

METHODS

The expression of miR-146a in serum, PBMC, and abdominal aorta tissues was measured in AAA patients.

RESULTS

We found that level of miR-146a in the serum and its expression in AAA tissues were significantly higher than that in healthy people or normal abdominal aorta tissues. Pearson's method analysis showed that miRNA-146a in the serum of AAA patients was negatively correlated with serum TNF-α, IFN-γ and CRP, and was positively correlated with serum IL-10. The luciferase reporter gene system confirmed that miR-146a targeted inhibition of CARD10 expression in THP-1 and human umbilical vein endothelial cells (HUVECs), and miR-146a was negatively correlated with the expression of CARD10 in the tissues/PBMC of AAA patients. In PBMC of healthy people, over-expression of miR-146a by transferring miR-146a-mimic could increase the expression of SIRT1 but decreased the expression of p65 and the level of TNF-α secretion. Moreover, HUVECs cellular activity change by TNF-α in a dose-dependent manner.

CONCLUSIONS

These results suggested that miR-146a suppressed the inflammation of peripheral blood in AAA patients by targeting CARD10, and miR-146a blocked the progression of AAA through CARD10/SIRT1/p65 pathway.

Impact of Sirtuin Enzymes on the Altered Metabolic Phenotype of Malignantly Transformed Cells

Sirtuins compose a unique collection of histone deacetylase enzymes that have a wide variety of enzymatic activities and regulate diverse cell functions such as cellular metabolism, longevity and energy homeostasis, mitochondrial function, and biogenesis. Impaired sirtuin functions or alterations of their expression levels may result in several pathological conditions and contribute to the altered metabolic phenotype of malignantly transformed cells in a significant manner. In the twenty-first century, principles of personalized anticancer treatment need to involve not only the evaluation of changes of the genetic material, but also the mapping of epigenetic and metabolic alterations, to both of which the contribution of sirtuin enzymes is fundamental. Since sirtuins are central players in the maintenance of cellular energy and metabolic homeostasis, they are key elements in the development of metabolic transformation of cancer cells referred to as the Warburg effect. Although its most well-known features are enhanced glycolysis and excessive lactate production, Warburg effect has several aspects involving both carbohydrate, lipid, and amino acid metabolism, among which different tumor types have different preferences. Therefore, energy supply of cancer cells can be impaired by a growing number of antimetabolite agents, for which appropriate vectors are strongly needed. However, data are controversial about their tumor suppressor or oncogenic properties, the biological effects of sirtuin enzymes strongly depend on the tissue microenvironment (TME) in which they are expressed. Immune cells are regarded as key players of TME. Sirtuins regulate the survival, activation, metabolism, and mitochondrial function of these cells, therefore, they are not only single elements, but key regulators of the network that determines anticancer immunity. Altered metabolism of tumor cells induces changes in the gene expression pattern of cells in TME, due to altered concentrations of metabolite cofactors of epigenetic modifiers including sirtuins. In summary, epigenetic and metabolic alterations in malignant diseases are influenced by sirtuins in a significant manner, and should be treated in a personalized approach. Since they often develop in early stages of cancer, broad examination of these alterations is required at time of the diagnosis in order to provide a personalized combination of distinct therapeutic agents.

FasL-PDPK1 Pathway Promotes the Cytotoxicity of CD8+ T Cells During Ischemic Stroke

CD8⁺ T cells are recognized as key players in exacerbation of ischemic stroke; however, the underlying mechanism in modulating the function of CD8⁺ T cells has not been completely elucidated. Here, we uncovered that FasL enhanced the cytotoxicity of CD8⁺ T cells to neurons after ischemic stroke. Inactivation of FasL specific on CD8⁺ T cells protected against brain damage and neuron loss. Proteomic analysis identified that PDPK1 functioned downstream of FasL signaling and inhibition of PDPK1 effectively reduced cytotoxicity of CD8⁺ T cells and improved ischemic neurological deficits. Taken together, these results highlight an intrinsic FasL-PDPK1 pathway regulating the cytotoxicity of CD8⁺ T cells in ischemic stroke.

lncRNA CCAT2 promotes radiotherapy resistance for human esophageal carcinoma cells via the miR‑145/p70S6K1 and p53 pathway

The long non‑coding RNA colon cancer‑associated transcript 2 (CCAT2) is abnormally expressed in various types of malignant tumor tissues and considered to be an oncogene, including for esophageal cancer (EC). Radiotherapy is an important and widely used cancer treatment. However, some patients with EC do not respond to radiotherapy. This study was designed to investigate effects of CCAT2 expression on radiotherapy dynamics for EC cells and to explore underlying molecular mechanisms. Reverse transcription‑quantitative PCR was used to measure CCAT2 expression in EC tissues, normal esophageal mucosa, EC cells and normal human esophageal epithelial cells. TUNEL assays were used to assess the effect of CCAT2 on X‑ray‑induced apoptosis of EC cells. Protein expression was detected by western blot. CCAT2 was highly expressed in EC tissues and EC cells, and was negatively associated with radiotherapy efficacy in patients with EC. In vitro, knockdown of CCAT2 enhanced radiosensitivity of EC cells and promoted apoptosis by increasing Bax/Bcl2 and active‑caspase 3/caspase 3 following X‑ray treatment. In addition, CCAT2 negatively regulated miR‑145 and P70 ribosomal protein S6 kinase 1 (p70S6K1) expression, and inhibited phosphorylation of Akt, ERK and p70S6K1 in EC cells. After X‑ray treatment, CCAT2 negatively regulated protein levels of p53, P21 and c‑Myc. These results showed that CCAT2 promoted the radiotherapy resistance of EC cells via negative regulation of the miR‑145/p70S6K1 and the p53 signaling pathways and associated elements may be potential targets for improving the sensitivity of EC radiotherapy.

Dual Deletion of the Sirtuins SIRT2 and SIRT3 Impacts on Metabolism and Inflammatory Responses of Macrophages and Protects From Endotoxemia

Sirtuin 2 (SIRT2) and SIRT3 are cytoplasmic and mitochondrial NAD-dependent deacetylases. SIRT2 and SIRT3 target proteins involved in metabolic, proliferation and inflammation pathways and have been implicated in the pathogenesis of neurodegenerative, metabolic and oncologic disorders. Both pro- and anti-inflammatory effects have been attributed to SIRT2 and SIRT3, and single deficiency in SIRT2 or SIRT3 had minor or no impact on antimicrobial innate immune responses. Here, we generated a SIRT2/3 double deficient mouse line to study the interactions between SIRT2 and SIRT3. SIRT2/3^−/− mice developed normally and showed subtle alterations of immune cell populations in the bone marrow, thymus, spleen, blood and peritoneal cavity that contained notably more anti-inflammatory B-1a cells and less NK cells. In vitro, SIRT2/3^−/− macrophages favored fatty acid oxidation (FAO) over glycolysis and produced increased levels of both proinflammatory and anti-inflammatory cytokines. In line with metabolic adaptation and increased numbers of peritoneal B-1a cells, SIRT2/3^−/− mice were robustly protected from endotoxemia. Yet, SIRT2/3 double deficiency did not modify endotoxin tolerance. Overall, these data suggest that sirtuins can act in concert or compensate each other for certain immune functions, a parameter to be considered for drug development. Moreover, inhibitors targeting multiple sirtuins developed for clinical purposes may be useful to treat inflammatory diseases.

SIRT4 silencing in tumor-associated macrophages promotes HCC development via PPARδ signalling-mediated alternative activation of macrophages

Background

The activation of tumour-associated macrophages (TAMs) contributes to the progression of hepatocellular carcinoma (HCC). SIRT4 acts as a tumour suppressor of tumour growth by regulating cell metabolism, inflammation, and anti-tumourigenesis. However, the involvement of SIRT4 in the activation of TAMs is unknown. Based on previous findings, the expression of SIRT4 in distinct groups of TAMs as well as the effect of SIRT4 silencing on macrophage polarization was investigated.

Methods

The expression of SIRT4 in HCC tissues and peritumour tissues was tested by qRT-PCR, western blotting and histological analysis. A Kaplan-Meier survival curve was generated based on the expression of SIRT4 in the HCC samples. Next, immunofluorescence staining was used to evaluate distinct groups of TAMs in human HCC samples, and the expression of SIRT4 in M1 and M2 TAMs was examined by flow cytometry. A homograft mouse model was used to assess the effect of SIRT4 silencing in TAMs on the development of HCC cells.

Results

SIRT4 was significantly downregulated in HCC tumour tissues, and the expression of SIRT4 in peritumour tissues was positively associated with survival in patients. We further found that downregulation of SIRT4 was associated with increased macrophage infiltration and a high ratio of M2/M1 macrophages in HCC peritumour tissues. Using gene interference, we found that SIRT4 silencing in TAMs significantly modulated the alternative activation of macrophages and promoted in vitro and in vivo HCC cell growth. Mechanistically, we revealed that HCM restricted the expression of SIRT4 in macrophages and promoted alternative activation of macrophages via the FAO-PPARδ-STAT3 axis. Furthermore, we also revealed that elevated MCP-1 expression induced by SIRT4 downregulation was responsible for increased TAM infiltration in peritumour tissues.

Conclusions

Overall, our results demonstrate that downregulation of SIRT4 in TAMs modulates the alternative activation of macrophages and promotes HCC development via the FAO-PPARδ-STAT3 axis. These results could provide a new therapeutic target for the treatment of HCC.

Switch of NAD Salvage to de novo Biosynthesis Sustains SIRT1-RelB-Dependent Inflammatory Tolerance

A typical inflammatory response sequentially progresses from pro-inflammatory, immune suppressive to inflammatory repairing phases. Although the physiological inflammatory response resolves in time, severe acute inflammation usually sustains immune tolerance and leads to high mortality, yet the underlying mechanism is not completely understood. Here, using the leukemia-derived THP-1 human monocytes, healthy and septic human peripheral blood mononuclear cells (PBMC), we report that endotoxin dose-dependent switch of nicotinamide adenine dinucleotide (NAD) biosynthesis pathways sustain immune tolerant status. Low dose endotoxin triggered nicotinamide phosphoribosyltransferase (NAMPT)-dependent NAD salvage activity to adapt pro-inflammation. In contrast, high dose endotoxin drove a shift of NAD synthesis pathway from early NAMPT-dependent NAD salvage to late indoleamine 2,3-dioxygenase-1 (IDO1)-dependent NAD de novo biosynthesis, leading to persistent immune suppression. This is resulted from the IDO1-dependent expansion of nuclear NAD pool and nuclear NAD-dependent prolongation of sirtuin1 (SIRT1)-directed epigenetics of immune tolerance. Inhibition of IDO1 activity predominantly decreased nuclear NAD level, which promoted sequential dissociations of immunosuppressive SIRT1 and RelB from the promoter of pro-inflammatory TNF-α gene and broke endotoxin tolerance. Thus, NAMPT-NAD-SIRT1 axis adapts pro-inflammation, but IDO1-NAD-SIRT1-RelB axis sustains endotoxin tolerance during acute inflammatory response. Remarkably, in contrast to the prevention of sepsis death of animal model by IDO1 inhibition before sepsis initiation, we demonstrated that the combination therapy of IDO1 inhibition by 1-methyl-D-tryptophan (1-MT) and tryptophan supplementation rather than 1-MT administration alone after sepsis onset rescued sepsis animals, highlighting the translational significance of tryptophan restoration in IDO1 targeting therapy of severe inflammatory diseases like sepsis.

Sirtuins as novel targets in the pathogenesis of airway inflammation in bronchial asthma

Sirtuins are NAD-dependent class III histone deacetylase, which modulate the epigenetic changes to influence the functions in normal and diseased conditions. Preclinical studies have described an increase in the levels of sirtuin 2 and decrease in the levels of sirtuin 6 in the lungs. Sirtuin 2 exerts proinflammatory actions and hence, its blockers reduce the airway inflammation and symptoms of asthma. On the other hand, sirtuin 6 is anti-inflammatory and its activators produce beneficial actions in asthma. The beneficial effects of sirtuin 6 have been attributed to decrease in acetylation of transcriptional factor GATA3 in the T cells, which is associated with decrease in the T_H2 immune response. However, there seems to be dual role of sirtuin 1 in airway inflammation as its proinflammatory as well as anti-inflammatory actions have been described in asthma. The anti-inflammatory actions of sirtuin 1 have been attributed to decrease in acetylation of GATA3 and inhibition of Akt/NF-kappaB signaling. On the other hand, proinflammatory actions of sirtuin 1 have been attributed to increase in the expression of HIF-1α and VEGF along with repression of PPAR-γ activity. The present review discusses the role of different sirtuins in the pathogenesis of bronchial asthma. Moreover, it also discusses sirtuin-triggered signaling pathways that may contribute in modulating the disease state of bronchial asthma.

Regulation of Monocyte-Macrophage Responses in Cirrhosis-Role of Innate Immune Programming and Checkpoint Receptors

Many aspects of the innate immune system have been studied in cirrhosis, and abnormalities have been described supporting both a pro-inflammatory and anti-inflammatory phenotype of myeloid cells. However, the findings of these studies vary by stage of disease and methodology. The recent description of the syndrome of acute-on-chronic liver failure (ACLF) has refined our understanding of the natural history of cirrhosis. In this context, we review the regulatory mechanisms at play that contribute to the immune abnormalities described in advanced liver disease. Specifically, we review the evidence for epigenetic mechanisms regulating monocyte phenotype, and the role of checkpoint receptors on regulating innate and adaptive immune cell function.

Frontline Science: Monocytes sequentially rewire metabolism and bioenergetics during an acute inflammatory response

Metabolism directs the severe acute inflammatory reaction of monocytes to guard homeostasis. This occurs by sequentially activating anabolic immune effector mechanisms, switching to immune deactivation mechanisms and then restoring immunometabolic homeostasis. Nuclear sirtuin 1 and mitochondrial pyruvate dehydrogenase kinase metabolically drive this dynamic and are druggable targets that promote immunometabolic resolution in septic mice and increase survival. We used unbiased metabolomics and a validated monocyte culture model of activation, deactivation, and partial resolution of acute inflammation to sequentially track metabolic rewiring. Increases in glycogenolysis, hexosamine, glycolysis, and pentose phosphate pathways were aligned with anabolic activation. Activation transitioned to combined lipid, protein, amino acid, and nucleotide catabolism during deactivation, and partially subsided during early resolution. Lipid metabolic rewiring signatures aligned with deactivation included elevated n-3 and n-6 polyunsaturated fatty acids and increased levels of fatty acid acylcarnitines. Increased methionine to homocysteine cycling increased levels of s-adenosylmethionine rate-limiting transmethylation mediator, and homocysteine and cysteine transsulfuration preceded increases in glutathione. Increased tryptophan catabolism led to elevated kynurenine and de novo biosynthesis of nicotinamide adenine dinucleotide from quinolinic acid. Increased branched-chain amino acid catabolism paralleled increases in succinyl-CoA. A rise in the Krebs cycle cis-aconitate-derived itaconate and succinate with decreased fumarate and acetyl-CoA levels occurred concomitant with deactivation and subsided during early resolution. The data suggest that rewiring of metabolic and mitochondrial bioenergetics by monocytes sequentially activates, deactivates, and resolves acute inflammation.

Sirtuin-1 in immunotherapy: A Janus-headed target

Sirtuin-1 (Sirt1), a member of the NAD-dependent sirtuin family of histone/protein deacetylases (HDAC), is an important target for immunotherapy due to its role in deacetylating the transcription factors Foxp3 and thymic retinoid acid receptor related orphan receptor gamma (RORγt). Sirt1 inhibition can increase Foxp3 acetylation and promote the production and functions of Foxp3⁺ T-regulatory (Treg) cells, whereas the acetylation of RORγt decreases its transcriptional activity DNA binding and decreases the differentiation of proinflammatory Th17 cells. Pharmacologic inhibitors of Sirt1 increase allograft survival and decrease autoimmune colitis and experimental allergic encephalomyelitis. However, in contrast to its role in T cells, Sirt1 has anti-inflammatory effects in myeloid cells, and, context dependent, in Th17 cells. Here, inhibition of Sirt1 can have proinflammatory effects. In addition to effects arising from the central role of Sirt1 in cellular metabolism and NAD-dependent reactions, such proinflammatory effects further complicate the potential of Sirt1 for therapeutic immunosuppression. This review aims to reconcile the opposing literature on pro- and anti-inflammatory effects of Sirt1, provides an overview of the role of Sir1 in the immune system, and discusses the pros and cons associated with inhibiting Sirt1 for control of inflammation and immune responses.

DNA Methylation and Transcription Factors Competitively Regulate SIRT4 Promoter Activity in Bovine Adipocytes: Roles of NRF1 and CMYB

Sirtuin 4 (SIRT4) belongs to the mitochondrial sirtuin protein family, a class of NAD⁺-dependent protein deacylases that remove post-translational acyl modifications from cellular substrates during the regulation of various biological pathways. SIRT4 has been shown to regulate lipid homeostasis. However, the mechanism by which the bovine SIRT4 gene is transcriptionally regulated remains unknown. To explore the molecular mechanism of SIRT4 expression, we obtained a 400-kb fragment of the 5'-regulatory region of bovine SIRT4 by molecular cloning, which contained a CpG island. Electrophoretic mobility shift assays and luciferase reporter gene assays identified the nuclear respiratory factor 1 (NRF1) and myb proto-oncogene protein (CMYB) binding sites as transcriptional repression and activation sites in the SIRT4 promoter region, respectively. We further verified that NRF1 and CMYB bind to the SIRT4 promoter using chromatin immunoprecipitation assays. In addition, from DNA methylation and reporter gene assays, results revealed that SIRT4 promoter activity was enhanced by demethylation. Further, NRF1-mediated transcriptional inhibition and CMYB-mediated transcriptional activation of SIRT4 expression were strengthened by demethylation during bovine adipocyte differentiation. Taken together, our results shed light on the mechanism underlying the promoter methylation and transcriptional regulation of SIRT4 expression in bovine adipocytes.