Increases in peripheral SIRT1: a new biological characteristic of asthma

Research progress of SIRTs activator resveratrol and its derivatives in autoimmune diseases

Autoimmune diseases (AID) have emerged as prominent contributors to disability and mortality worldwide, characterized by intricate pathogenic mechanisms involving genetic, environmental, and autoimmune factors. In response to this challenge, a growing body of research in recent years has delved into genetic modifications, yielding valuable insights into AID prevention and treatment. Sirtuins (SIRTs) constitute a class of NAD-dependent histone deacetylases that orchestrate deacetylation processes, wielding significant regulatory influence over cellular metabolism, oxidative stress, immune response, apoptosis, and aging through epigenetic modifications. Resveratrol, the pioneering activator of the SIRTs family, and its derivatives have captured global scholarly interest. In the context of AID, these compounds hold promise for therapeutic intervention by modulating the SIRTs pathway, impacting immune cell functionality, suppressing the release of inflammatory mediators, and mitigating tissue damage. This review endeavors to explore the potential of resveratrol and its derivatives in AID treatment, elucidating their mechanisms of action and providing a comprehensive analysis of current research advancements and obstacles. Through a thorough examination of existing literature, our objective is to advocate for the utilization of resveratrol and its derivatives in AID treatment while offering crucial insights for the formulation of innovative therapeutic approaches.

SIRT1: An Intermediator of Key Pathways Regulating Pulmonary Diseases

Silent information regulator type-1 (SIRT1), a nicotinamide adenine dinucleotide+-dependent deacetylase, is a member of the sirtuins family and has unique protein deacetylase activity. SIRT1 participates in physiological as well as pathophysiological processes by targeting a wide range of protein substrates and signalings. In this review, we described the latest progress of SIRT1 in pulmonary diseases. We have introduced the basic information and summarized the prominent role of SIRT1 in several lung diseases, such as acute lung injury, acute respiratory distress syndrome, chronic obstructive pulmonary disease, lung cancer, and aging-related diseases.

Investigating the T regulatory cells and Sirtuin-I serum level in immunotherapy treated house dust mite allergic asthma patients

OBJECTIVES

House dust mite aeroallergens are predominant triggers of frequent asthma attacks among adults and children. The intensity of asthma and immune reaction necessitates treatment alternatives based on adjusting chosen immunity biomarkers to control the exacerbation of symptoms and establish long-term immune tolerance. In this study, we selected CD4+CD25+Foxp3+ regulatory T cells (Tregs), FOXP3, and Sirtuin-1 as they are known to have a potential role in the immune reaction in different allergic diseases. We investigated their interplay during HDM allergic asthma and its respective immunotherapy.

METHODS

Eighty-four subjects were divided into 3 groups; healthy controls (CT), HDM asthma patients without immunotherapy (WOIT), and HDM asthma patients treated with subcutaneous immunotherapy for 6 months before recruitment (WIT). They were enrolled according to the pulmonary function, skin prick tests, and HDM-specific IgE. CD4+ CD25+ and CD4+ CD25+ FOXP3+hi T cells Cell percentages, FOXP3 gene expression, and Sirtuin-1 (Sirt1) serum level were analyzed.

RESULTS

We found that there is a significant difference between WOIT and WIT groups in the CD4+ CD25+ and CD4+ CD25+ FOXP3+hi T cell percentages. While there is no statistically significant difference between WOIT and WIT groups in FOXP3 level. On the controversy, the SIRT1 level in the CT group (4.53 ± 3.880) significantly decreased in the WOIT and WIT groups.

CONCLUSION

This study revealed that both CD4 CD25 and CD4 CD25 high FOXP3 cell percentages increased in the WIT group and declined in the WOIT group. While, FOXP3 gene expression increased in both groups. In addition, the Sirt1 serum level showed some improvement in WIT group after a serious drop in the WOIT group comparing with the CT group. The modulation of these biomarkers for the remission and control of allergic asthma can be a prognostic outcome of immunotherapy which needs to be confirmed by larger scale studies.

Inhibition of xanthine oxidase by allopurinol suppresses HMGB1 secretion and ameliorates experimental asthma

BACKGROUND

Extracellular high mobility group box 1 (HMGB1) is a key mediator in driving allergic airway inflammation and contributes to asthma. Yet, mechanism of HMGB1 secretion in asthma is poorly defined. Pulmonary metabolic dysfunction is recently recognized as a driver of respiratory pathology. However, the altered metabolic signatures and the roles of metabolic to allergic airway inflammation remain unclear.

METHODS

Male C57BL/6 J mice were sensitized and challenged with toluene diisocyanate (TDI) to generate a chemically induced asthma model. Pulmonary untargeted metabolomics was employed. According to results, mice were orally administered allopurinol, a xanthine oxidase (XO) inhibitor. Human bronchial epithelial cells (16HBE) were stimulated by TDI-human serum albumin (HSA).

RESULTS

We identified the purine metabolism was the most enriched pathway in TDI-exposed lungs, corresponding to the increase of xanthine and uric acid, products of purine degradation mediated by XO. Inhibition of XO by allopurinol ameliorates TDI-induced oxidative stress and DNA damage, mixed granulocytic airway inflammation and Th1, Th2 and Th17 immunology as well as HMGB1 acetylation and secretion. Mechanistically, HMGB1 acetylation was caused by decreased activation of the NAD+-sirtuin 1 (SIRT1) axis triggered by hyperactivation of the DNA damage sensor poly (ADP-ribose)-polymerase 1 (PARP-1). This was rescued by allopurinol, PARP-1 inhibitor or supplementation with NAD+ precursor in a SIRT1-dependent manner. Meanwhile, allopurinol attenuated Nrf2 defect due to SIRT1 inactivation to help ROS scavenge.

CONCLUSIONS

We demonstrated a novel regulation of HMGB1 acetylation and secretion by purine metabolism that is critical for asthma onset. Allopurinol may have therapeutic potential in patients with asthma.

Sirtuin 1 serum concentration in healthy children - dependence on sex, age, stage of puberty, body weight and diet

Introduction

Sirtuin 1 (SIRT1) is known to be involved in sensing cellular energy levels and regulating energy metabolism. This study aimed to evaluate fasting serum SIRT1 levels in healthy children, and to analyse the influence of age, sex, puberty, body weight, height, and diet on its concentration.

Methods

47 healthy children aged 4-14 with weight and height within normal range and no chronic disease were included into the study. Fasting serum SIRT1 concentrations were estimated by Enzyme Linked Immunosorbent Assay (ELISA).

Results

Results showed that serum SIRT1 concentrations in healthy children did not differ with respect to sex, age, height, weight and puberty. Whereas, it appeared that a higher frequency of fruits, vegetables and dairy products consumption was associated with an increase in serum SIRT1 levels.

Discussion

Studying SIRT1 in the context of children's health may have implications for a broader understanding of growth processes, pubertal development, metabolic disorders and nutrition.

Emerging roles of SIRT1 activator, SRT2104, in disease treatment

Silent information regulator 1 (SIRT1) is a NAD+-dependent class III deacetylase that plays important roles in the pathogenesis of numerous diseases, positioning it as a prime candidate for therapeutic intervention. Among its modulators, SRT2104 emerges as the most specific small molecule activator of SIRT1, currently advancing into the clinical translation phase. The primary objective of this review is to evaluate the emerging roles of SRT2104, and to explore its potential as a therapeutic agent in various diseases. In the present review, we systematically summarized the findings from an extensive array of literature sources including the progress of its application in disease treatment and its potential molecular mechanisms by reviewing the literature published in databases such as PubMed, Web of Science, and the World Health Organization International Clinical Trials Registry Platform. We focuses on the strides made in employing SRT2104 for disease treatment, elucidating its potential molecular underpinnings based on preclinical and clinical research data. The findings reveal that SRT2104, as a potent SIRT1 activator, holds considerable therapeutic potential, particularly in modulating metabolic and longevity-related pathways. This review establishes SRT2104 as a leading SIRT1 activator with significant therapeutic promise.

HDAC3-mediated lncRNA ZFAS1 inhibited IL-13-induced secretion of proinflammatory cytokines in nasal epithelial cells by regulating the miR-7-5p/SIRT1 pathway

Allergic rhinitis (AR) is a disease that is difficult to cure and accompanies the patient's life. Proinflammatory cytokines (GM-CSF and eotaxin) and MUC5AC are key mediators promoting AR progression. Herein, the function of lncRNA ZFAS1 in AR was investigated. Nasal epithelial cells (NECs) were subjected to 50 ng/mL IL-13 for 24 h to construct an AR cell model. The mRNA and protein expressions were assessed using qRT-PCR and western blot. The levels of GM-CSF, eotaxin, IL-1β, IL-6, TNF-α and MUC5AC in cell supernatant were examined by ELISA. The binding relationships between HDAC3, ZFAS1, miR-7-5p and SIRT1 were analysed using dual luciferase reporter or ChIP assays. Herein, our results displayed that ZFAS1 and SIRT1 were lowly expressed in AR, while miR-7-5p and HDAC3 were highly expressed. Functional experiments displayed that ZFAS1 overexpression suppressed IL-13-induced proinflammatory cytokines and mucin production in NECs. The highly expressed HDAC3 in AR inhibited ZFAS1 expression by binding with ZFAS1 promoter. In addition, our experiments revealed that ZFAS1 targeted miR-7-5p, and miR-7-5p targeted SIRT1. As expected, miR-7-5p overexpression or SIRT1 silencing abrogated ZFAS1 upregulation's repression on IL-13-induced proinflammatory cytokines and MUC5AC secretory levels in NECs. ZFAS1 suppressed proinflammatory cytokines, inflammatory cytokines, and MUC5AC secretory levels in AR by regulating the miR-7-5p/SIRT1 axis. Thus, our work suggested that ZFAS1 might serve as a novel target for AR treatment and prevention.

Investigating Forkhead Box O Transcription Factor 1 Gene's Relation to Immunoglobulin E in House Dust Mite-Allergic Asthma Patients

House dust mite (HDM)-allergic asthma is an abnormal immune response to extrinsic aeroallergens found in human vicinities. Studying the role of the associated immunity biomarkers and their interplay helps in discovering novel therapeutic strategies that can be used in adjunct with effective long-term immunotherapy. This study investigates the total serum IgE, FoxO1, and Sirtuin 1 (SIRT1) gene expressions in HDM-allergic asthma patients. We enrolled 40 patients for each of the following three groups: an HV group of healthy volunteers and HDM/AA and HDM/SCIT groups of HDM-allergic asthma patients who did not and who did receive immunotherapy before recruitment in this study, respectively. The results elucidated that total IgE was strikingly elevated in the HDM/AA group and showed little decline in the HDM/SCIT group. Both FoxO1 and SIRT1 gene expressions showed the highest levels in the HDM/SCIT group. There was a negative correlation between total IgE and both FoxO1 and SIRT1 in the HDM/AA group while there was a positive correlation with SIRT1 in the HDM/SCIT group. In conclusion, the interplay of the three immunity biomarkers related to HDM-allergic asthma after the course of immunotherapy treatment suggests further, broader studies on the feasibility of their role as immunity biomarkers in the control and remission of HDM-allergic asthma.

Echinacoside alleviates airway remodeling and inflammation in an ovalbumin-induced neonatal mouse model of asthma by modulating the SIRT1-NF-κB pathway

PURPOSE

Echinacoside (ECH) has been reported to have anti-inflammatory and anti-immune effects, and may be effective for treating asthma. This study aimed to investigate the effect of ECH on asthma.

METHODS

A mouse model of asthma was established by ovalbumin (OVA) induction, and the effect of ECH on airway remodeling in mice was evaluated using the Periodic Acid-Schiff stain and enzyme-linked immunosorbent serologic assay (ELISA). Additionally, the effect of ECH on collagen deposition in asthmatic mice was assessed using Western blotting (WB) analysis, and response to airway inflammation was evaluated by ELISA. The signaling pathway regulated by ECH was also investigated using WB.

RESULTS

Our findings demonstrated that ECH restored OVA-induced increase in mucin, -immunoglobulin E, and respiratory resistance. ECH also alleviated OVA-induced collagen -deposition, including collagen I, collagen III, alpha smooth muscle actin, and epithelial (E)-cadherin. Moreover, ECH restored the elevated levels of interleukin (IL)-13, IL-17, and the increased -number of macrophages, eosinophils, lymphocytes, and neutrophills induced by OVA. ECH mainly exerted its regulatory effects by modulating the silent mating type information regulation 2 homolog 1 (Sirtuin 1/SIRT1)-nuclear factor kappa B (NF-κB) signaling pathway in the mouse models of asthma.

CONCLUSION

This study highlights the therapeutic potential of ECH for attenuating airway remodeling and inflammation in an OVA-induced neonatal mouse model of asthma through the modulation of SIRT1/NF-κB pathway.

Relief of ovalbumin-induced airway remodeling by the glycyl-l-histidyl-l-lysine-Cu2+ tripeptide complex via activation of SIRT1 in airway epithelial cells

Fixed airflow limitation (FAO), prevalent in patients with severe or difficult-to-treat asthma, is mainly caused by airway remodeling. Airway remodeling is initiated by inflammation and involves subsequent pathological changes. Glycyl-l-histidyl-l-lysine (GHK) is a matrikine with anti-inflammatory and antioxidant effects, naturally existing in human tissue. At present, the GHK level in human plasma and whether it is related to airway remodeling of asthma remain unclear. This study was conducted to determine how GHK is involved in airway remodeling in asthma. Our result showed that the plasma GHK levels of patients with asthma were significantly lower than those of age-matched healthy controls. In asthma patients, plasma GHK levels display a moderate correlation with FEF_25-75%, and patients with FAO had significantly lower GHK levels. Ovalbumin-induced mice of asthma model treated with PBS or GHK-Cu (a form of GHK with higher bioavailability) were used to evaluate the effect of exogenous GHK supplement on airway remodeling. GHK-Cu administration alleviated airway remodeling, as reflected by decreased peribronchial collagen deposition and airway mucus secretion, and suppressed epithelial-mesenchymal transition. The therapeutical effect related to decreased TGF-β1 level. Successively, network pharmacology and the validation data of experiments in vivo and vitro demonstrated that GHK-Cu decreased TGF-β1 level by increasing SIRT1 expression and activating SIRT1 deacetylation in airway epithelial cells, thereby alleviating airway remodeling. Collectively, decreased plasma GHK levels were related to FAO in asthma patients. Through the direct binding and activation of SIRT1, exogenous GHK-Cu administration alleviated airway remodeling in asthmatic mice.

Progranulin deficiency suppresses allergic asthma and enhances efferocytosis via PPAR-γ/MFG-E8 regulation in macrophages

Efferocytosis can resolve airway inflammation and enhance airway tolerance in allergic asthma. While previous work has reported that progranulin (PGRN) regulated macrophage efferocytosis, but it is unclear whether PGRN-mediated efferocytosis is associated with asthma. Here, we found that in an ovalbumin (OVA)-induced allergic asthma model, the airway inflammation was suppressed and the apoptosis in lung tissues was ameliorated in PGRN-deficient mice. In contrast, PGRN knockdown in human bronchial epithelial cells increased apoptosis in vitro. Furthermore, PGRN-deficient macrophages had significantly stronger efferocytosis ability than wild type (WT) macrophages both in vitro and in vivo. PGRN-deficient peritoneal macrophages (PMs) exhibited increased expression of genes associated with efferocytosis including milk fat globule-epidermal growth factor 8 (MFG-E8), peroxisome proliferator-activated receptor gamma (PPAR-γ) and sirtuin1 (SIRT1) and increased capacity to produce the anti-inflammatory mediator interleukin (IL)-10 during efferocytosis. GW9662, the inhibitor of PPAR-γ, abolished increased efferocytosis and MFG-E8 expression in PGRN-deficient PMs suggesting that PGRN deficiency enhanced MFG-E8-mediated efferocytosis through PPAR-γ. Correspondingly, efferocytosis genes were increased in the lungs of OVA-induced PGRN-deficient mice. GW9662 treatment reduced MFG-E8 expression but did not significantly affect airway inflammation. Our results demonstrated that PGRN deficiency enhanced efferocytosis via the PPAR-γ/MFG-E8 pathway and this may be one of the reasons PGRN deficiency results in inhibition of airway inflammation in allergic asthma.

Mesenchymal Stem/Stromal Cells in Asthma Therapy: Mechanisms and Strategies for Enhancement

Asthma is a complex and heterogeneous disease characterized by chronic airway inflammation, airway hyperresponsiveness, and airway remodeling. Most asthmatic patients are well-established using standard treatment strategies and advanced biologicals. However, a small group of patients who do not respond to biological treatments or are not effectively controlled by available treatment strategies remain a clinical challenge. Therefore, new therapies are urgently needed for poorly controlled asthma. Mesenchymal stem/stromal cells (MSCs) have shown therapeutic potential in relieving airway inflammation and repairing impaired immune balance in preclinical trials owing to their immunomodulatory abilities. Noteworthy, MSCs exerted a therapeutic effect on steroid-resistant asthma with rare side effects in asthmatic models. Nevertheless, adverse factors such as limited obtained number, nutrient and oxygen deprivation in vitro, and cell senescence or apoptosis affected the survival rate and homing efficiency of MSCs, thus limiting the efficacy of MSCs in asthma. In this review, we elaborate on the roles and underlying mechanisms of MSCs in the treatment of asthma from the perspective of their source, immunogenicity, homing, differentiation, and immunomodulatory capacity and summarize strategies to improve their therapeutic effect.

Bergenin ameliorates airway inflammation and remodeling in asthma by activating SIRT1 in macrophages to regulate the NF-κB pathway

Airway inflammation and remodeling are critical pathological changes in asthma, and macrophage activation plays a vital role in this process. Sirtuin 1 (SIRT1) reduces airway inflammation by affecting macrophages in asthma. This study aimed to investigate the potential benefit and underlying mechanism of the SIRT1 agonist bergenin as a treatment for asthma. We performed in vivo and in vitro experiments by establishing a Sirt1^fl/fl-LysMcre mouse asthma model and using the alveolar macrophage-like cell line MH-S, respectively. Our results show that Sirt1^fl/fl-LysMcre asthmatic mice exhibited more severe airway inflammation and airway remodeling than wild-type mice. As an activator of SIRT1, bergenin attenuated asthmatic airway pathology and reduced production of interleukins 1β, IL-5, IL-6, and matrix metalloproteinase 9 (MMP-9) in wild-type asthmatic mice. However, the therapeutic effects of bergenin were significantly attenuated in Sirt1^fl/fl-LysMcre asthmatic mice or following coadministration with the SIRT1 inhibitor EX-527. Further experiments showed that activation of SIRT1 by bergenin deacetylates nuclear factor κB and hinders its nuclear translocation, thereby affecting IL-1β, IL-5, IL-6, and MMP-9 production by regulating transcriptional activity. Our study suggests that bergenin can improve asthma-induced airway inflammation and remodeling by activating SIRT1 in macrophages.

Roles of sirtuins in asthma

Sirtuins are nicotinamide adenine dinucleotide (NAD⁺)-dependent lysine deacylases and deacetylases that participate in a variety of cellular processes, including transcriptional activity, energy metabolism, DNA damage response, inflammation, apoptosis, autophagy, and oxidative stress. As a result, sirtuins are linked to multiple pathophysiological processes, such as cardiovascular diseases, metabolic diseases, autoimmune diseases, infectious diseases, and respiratory diseases. Asthma is the most common respiratory disease, which is characterized by airway inflammation and airway remodeling. Accumulating evidence has indicated that sirtuins are involved in the pathogenesis of asthma. Furthermore, some studies have suggested that sirtuin modulators are potential agents for the treatment of asthma via alteration of the expression or activity of sirtuins. In this review, we illustrate the role of sirtuins in asthma, discuss related molecular mechanisms, and evaluate the sirtuins-targeted therapy for asthma.

Sirtuins-Novel Regulators of Epigenetic Alterations in Airway Inflammation

Histone modification is an important epigenetic alteration, and histone deacetylases are involved in the occurrence and development of various respiratory diseases. Sirtuins (SIRTs) have been demonstrated to play an important role in the formation and progression of chronic inflammatory diseases of the respiratory tract. SIRTs participate in the regulation of oxidative stress and inflammation and are related to cell structure and cellular localization. This paper summarizes the roles and mechanisms of SIRTs in airway inflammation and describes the latest research on SIRT modulators, aiming to provide a theoretical basis for the study of potential epigenetic alteration-inducing drug targets.

Nuclear Sirtuins and the Aging of the Immune System

The immune system undergoes major changes with age that result in altered immune populations, persistent inflammation, and a reduced ability to mount effective immune responses against pathogens and cancer cells. Aging-associated changes in the immune system are connected to other age-related diseases, suggesting that immune system rejuvenation may provide a feasible route to improving overall health in the elderly. The Sir2 family of proteins, also called sirtuins, have been broadly implicated in genome homeostasis, cellular metabolism, and aging. Sirtuins are key responders to cellular and environmental stress and, in the case of the nuclear sirtuins, they do so by directing responses to chromatin that include gene expression regulation, retrotransposon repression, enhanced DNA damage repair, and faithful chromosome segregation. In the immune system, sirtuins instruct cellular differentiation from hematopoietic precursors and promote leukocyte polarization and activation. In hematopoietic stem cells, sirtuins safeguard quiescence and stemness to prevent cellular exhaustion. Regulation of cytokine production, which, in many cases, requires NF-κB regulation, is the best-characterized mechanism by which sirtuins control innate immune reactivity. In adaptive immunity, sirtuins promote T cell subset differentiation by controlling master regulators, thereby ensuring an optimal balance of helper (Th) T cell-dependent responses. Sirtuins are very important for immune regulation, but the means by which they regulate immunosenescence are not well understood. This review provides an integrative overview of the changes associated with immune system aging and its potential relationship with the roles of nuclear sirtuins in immune cells and overall organismal aging. Given the anti-aging properties of sirtuins, understanding how they contribute to immune responses is of vital importance and may help us develop novel strategies to improve immune performance in the aging organism.

Pterostilbene suppresses oxidative stress and allergic airway inflammation through AMPK/Sirt1 and Nrf2/HO-1 pathways

Introduction

Pterostilbene (Pts) may be used for allergic asthma treatment. The AMPK/Sirt1 and Nrf2/HO‐1 pathways are potential targets for asthma treatement. However, the relationship between Pts and AMPK/Sirt1 and Nrf2/HO‐1 pathways in asthma is unclear. Herein, we aim to explore the pharmacological effects of Pts on oxidative stress and allergic inflammatory response as well as the mechanism involving AMPK/Sirt1 and Nrf2/HO‐1 pathways.

Methods

Asthma model was established in mice with ovalbumin (OVA). The model mice were treated by different concentrations of Pts. Lung pathological changes were observed through histological staining. In vitro, lipopolysaccharide (LPS)‐stimulated 16HBE cells were treated with Pts. The siAMPKα2, siSirt1 and siNrf2 knockdown, and treatment with compound C, EX‐527 or ML385 were also performed in 16HBE cells. Enzyme‐linked immunosorbent assay was used to detect interleukin‐4 (IL‐4), IL‐13, IL‐5, total and OVA specific immunoglobulin E (IgE), and interferon γ (IFN‐γ). Pneumonography was used to measure the airway hyperreactivity (AHR). Superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) levels were also detected. Immunohistochemistry, Western blot and immunofluorescence were used to measure protein levels.

Results

Pts significantly attenuated lung inflammatory cell infiltration and goblet cell proliferation. Meanwhile, Pts treatment could reduce IL‐4, IL‐13, IL‐5, and IgE (total and OVA specific) levels in the asthma model mice. However, IFN‐γ in bronchoalveolar lavage fluid was elevated. In addition, Pts reduced AHR. We also found that Pts treatment promoted serum SOD and CAT, and reduced MDA. In vitro results showed that Pts treatment promoted iNOS, TNF‐α, COX‐2, IL‐1β, and IL‐6 expressions in 16HBE cells, prolonged G0/G1 phase of the cell cycle, and resulted in a shortened G2M phase. Moreover, we found that Pts promoted the phosphorylation of AMPK in 16HBE, and meanwhile inhibited the increase of ROS induced by LPS. Additionally, Pts treatment inhibited p‐AMPK, Sirt1, Nrf2 and HO‐1, which in turn leads to the alleviation of AMPK/Sirt1 and Nrf2/HO‐1 pathways.

Conclusion

Pts alleviated oxidative stress and allergic airway inflammation via regulation of AMPK/Sirt1and Nrf2/HO‐1 signaling pathways.

The Serum SIRT1 Protein is Associated with the Severity of Injury and Neurological Recovery in Mice with Traumatic Spinal Cord Injury

The present study aimed to investigate the association between the serum SIRT1 protein and the severity of spinal cord injury (SCI) as well as the neurological recovery in mice. In this study, the wild-type (WT), Mx1-Cre⁺ SIRT1^loxP/loxP (Mx1), and LCK-Cre⁺SIRT1^loxP/loxP (LCK) mice were subjected to sham surgery, mild, moderate, or severe SCI, respectively. The serum was collected at intervals of 12 h, 1 day (d), 3 d, 5 d, 7 d, 10 d, 14 d, and 21 d after the injury. The locomotor function of all the animals was assessed using the Basso mouse scale (BMS) and the serum SIRT1 proteins were analyzed using enzyme-linked immunosorbent assay (ELISA). The results demonstrated that about 7-10 d after SCI, the levels of SIRT1 protein in the serum correlated significantly with the severity of the injury and at 28 d post-injury, there was a distant neurological recovery (BMS score). The serum SIRT1 concentration in both the Mx1 and LCK mice in the sham group was significantly reduced compared to that in the WT mice, and there was a delayed increase in the serum SIRT1 levels after injury. These findings indicate that the SIRT1 concentrations in the serum of the SCI mice closely correlated with the acute severity and neurological outcome.

Myeloid-specific SIRT1 deletion exacerbates airway inflammatory response in a mouse model of allergic asthma

Sirtuin 1 (SIRT1) is a class III histone deacetylase that exerts an anti-inflammatory effect in airway diseases. Activated macrophages play an important role in asthma. However, the roles of SIRT1 on allergic airway inflammation in macrophages remain largely unexplored. In this study, we aimed to determine the roles of SIRT1 on allergic airway inflammation in macrophages. The effect of myeloid-specific SIRT1 deletion (Sirt1^fl/fl-LysMcre) on airway inflammation was assessed by using in vivo models of asthma following allergen exposure and in vitro culture of primary bone marrow–derived macrophages (BMDMs) exposed to house dust mite (HDM). We observed that Sirt1^fl/fl-LysMcre mice substantially enhanced airway inflammation and mucus production in response to allergen exposure. Expression of chemokine ligand (CXCL) 2, interleukin (IL)-1β, and tumor necrosis factor (TNF)-α were reduced in BMDMs with myeloid-specific deletion of Sirt1 after stimulation of HDM. Moreover, SIRT1 suppressed the inflammatory cytokines expression in BMDMs partially via the ERK/p38 MAPK pathways. Our study demonstrated that SIRT1 suppresses the allergic airway inflammation in macrophages, and suggested that activation of SIRT1 in macrophages may represent therapeutic strategy for asthma.

Clinical characteristics of allergic bronchopulmonary aspergillosis in patients with and without bronchiectasis

OBJECTIVE

Allergic bronchopulmonary aspergillosis (ABPA) is classified radiologically as serologic ABPA (ABPA-S) or ABPA with central bronchiectasis (ABPA-CB). This retrospective case series study aimed to describe and compare the clinical characteristics of both forms of ABPA.

METHODS

Patients with ABPA treated in the hospital between February 2011 and June 2019 were enrolled and were divided into ABPA-S and ABPA-CB groups based on whether their cases were complicated with central bronchiectasis. Demographic data, symptoms, laboratory values, comorbidities, and image findings were collected. ABPA-S patients were followed up retrospectively through medical records.

RESULTS

Ninety-three (93) patients were enrolled, including 74 ABPA-CB patients and 19 ABPA-S patients. The most common predisposing condition was asthma (36.6%), with a median course of 30 years (IQR 13-42.5) prior to ABPA diagnosis. Patients of 54.8% had been misdiagnosed, with ABPA-S more likely than ABPA-CB to have been misdiagnosed as asthma (p < 0.01). Obstructive ventilation dysfunction and mixed ventilation dysfunction were found in 21 patients (22.6%) and 16 patients (17.2%), respectively. Compared with ABPA-S, ABPA-CB had a higher median blood eosinophil count (880 vs. 700 cells/μl), serum IgE (2957 vs. 2616 IU/ml), and Aspergillus fumigatus specific-IgE (20.6 vs. 7.31 kUA/L), although these findings were not statistically significant. Three ABPA-S patients developed bronchiectasis during follow-up and experienced relapses more than twice.

CONCLUSIONS

Our findings suggested that the clinical characteristics between ABPA-CB and ABPA-S were mostly similar. ABPA-S had a relatively lower immunological activity level than ABPA-CB but was still immunologically active and could develop bronchiectasis.

Virus-Induced Asthma Exacerbations: SIRT1 Targeted Approach

The prevalence of asthma has increased worldwide. Asthma exacerbations triggered by upper respiratory tract viral infections remain a major clinical problem and account for hospital admissions and time lost from work. Virus-induced asthma exacerbations cause airway inflammation, resulting in worsening asthma and deterioration in the patients’ quality of life, which may require systemic corticosteroid therapy. Despite recent advances in understanding the cellular and molecular mechanisms underlying asthma exacerbations, current therapeutic modalities are inadequate for complete prevention and treatment of these episodes. The pathological role of cellular senescence, especially that involving the silent information regulator 2 homolog sirtuin (SIRT) protein family, has recently been demonstrated in stable and exacerbated chronic respiratory disease states. This review discusses the role of SIRT1 in the pathogenesis of bronchial asthma. It also discusses the role of SIRT1 in inflammatory cells that play an important role in virus-induced asthma exacerbations. Recent studies have hypothesized that SIRT1 is one of major contributors to cellular senescence. SIRT1 levels decrease in Th2 and non-Th2-related airway inflammation, indicating the role of SIRT1 in several endotypes and phenotypes of asthma. Moreover, several models have demonstrated relationships between viral infection and SIRT1. Therefore, targeting SIRT1 is a novel strategy that may be effective for treating virus-induced asthma exacerbations in the future.

SIRT1 relieves Necrotizing Enterocolitis through inactivation of Hypoxia-inducible factor (HIF)-1a

Necrotizing enterocolitis (NEC) is a major cause of mortality and morbidity in newborns, characterized by inflammatory intestinal necrosis. Sirtuin-1 (SIRT1), a NAD-dependent deacetylase, is involved in multiple biological functions. It has been reported that SIRT1 was downregulated in NEC tissues. However, the precise role of SIRT1 in NEC progress remains unknown. In this study, we found that SIRT1 was decreased in serum samples of NEC patients, associated with an inflammation response. an in vitro model was established by using LPS-induced NEC-like cell in this study. The results indicate that overexpression of SIRT1 inhibited the cell apoptosis induced by LPS. Besides, overexpression of SIRT1 suppressed the high expression of proinflammatory factors (IL-6, IL-8, and TNF-α), the decrease of transepithelial electrical resistance (TEER), and the decline expression of tight junction proteins (ZO-1, ZO-2, and Claudin-4) induced by LPS in Caco-2 cells. What is more, serum HIF-1α was increased in NEC patients. SIRT1 overexpression suppressed the expression and activity of HIF-1a, while knockdown of SIRT1 made the opposite effect. In summary, this study indicates that overexpression of SIRT1 alleviates the inflammation response and intestinal epithelial barrier dysfunction through regulating the expression and inactivation of HIF-1a.

Suppression of sirtuin 1 alleviates airway inflammation through mTOR‑mediated autophagy

Sirtuin 1 (SIRT1) is involved in the pathogenesis of allergic asthma. This study aimed to investigate whether EX-527, a specific SIRT1 inhibitor, exerted suppressive effects on allergic airway inflammation in mice submitted to ovalbumin (OVA) inhalation. In addition, this study assessed whether such a protective role was mediated by autophagy suppression though mammalian target of rapamycin (mTOR) activation. Female C57BL/6 mice were sensitized to OVA and EX-527 (10 mg/kg) was administered prior to OVA challenge. The study found that EX-527 reversed OVA-induced airway inflammation, and reduced OVA-induced increases in inflammatory cytokine expression, and total cell and eosinophil counts in bronchoalveolar lavage fluid. In addition, EX-527 enhanced mTOR activation, thereby suppressing autophagy in allergic mice. To assess whether EX-527 inhibited airway inflammation in asthma through the mTOR-mediated autophagy pathway, rapamycin was administered to mice treated with EX-527 after OVA sensitization. All effects induced by EX-527, including increased phosphorylated-mTOR and decreased autophagy, were abrogated by rapamycin treatment. Taken together, the present findings indicated that EX-527 may inhibit allergic airway inflammation by suppressing autophagy, an effect mediated by mTOR activation in allergic mice.

Protective effect of MOTS-c on acute lung injury induced by lipopolysaccharide in mice

MOTS-c (mitochondrial open-reading-frame of the twelve S rRNA-c), a mitochondrial-derived 16-amino acid peptide, targets the methionine-folate cycle, increases 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) levels, and eventually activates AMP-activated protein kinase (AMPK). AMPK activation can attenuate neutrophil pro-inflammatory activity and attenuates lipoteichoic acid (LTA) and lipopolysaccharide (LPS) induced acute lung injury (ALI) in mice. However, to our knowledge, the role of MOTS-c in LPS-induced ALI remains unclear. Hence, we investigated the potential effectiveness and underlying mechanism of MOTS-c against LPS-induced ALI in mice. The intraperitoneal administration of MOTS-c (5 mg/kg, i.p., bid, 6 days) before intratracheal LPS instillation attenuated body weight loss and pulmonary edema, inhibited neutrophilic tissue infiltration in lung tissue, downregulated the expression of cytokine-induced neutrophil chemoattractant-1 (CINC-1) and intercellular cell adhesion molecule-1 (ICAM-1) in lung tissues, decreased the levels of TNF-α, IL-1β, and IL-6, and increased the expression of IL-10 and SOD in serum, lung tissue, and bronchoalvelolar lavage fluid (BALF). Moreover, MOTS-c treatment significantly promoted p-AMPKα and SIRT1 expression and suppressed LPS-induced ERK, JNK, p38, p65, and STAT3 activation in the mouse lung tissues. Collectively, these findings suggest that MOTS-c plays important roles in protecting the lungs from the inflammatory effects of LPS-induced ALI. The effects of MOTS-c are probably orchestrated by activating AMPK and SIRT1, inhibiting ERK, JNK, p65, and STAT3 signaling pathways. Thus, MOTS-c appears to be a novel and promising candidate for the treatment of ALI.

miR-221 participates in the airway epithelial cells injury in asthma via targeting SIRT1

AIM OF THE STUDY

To investigate the role of microRNA-221 (miR-221) in the airway epithelial cell injury in asthma and delineate the underlying mechanism that may involve with SIRT1.

MATERIALS AND METHOD

Bronchial epithelial cells from asthma patients and healthy controls were obtained by bronchoscopic brushing. The miR-221 and SIRT1 mRNA level in collected cells were detected by qRT-CPR. BEAS2B cell lines were cultured in vitro. In order to up-regulate miR-221 and SIRT1, miR-221 mimic and pcDNA3.1-SIRT1 vector was transfected into BEAS2B cells, respectively. The expression changes of miR-221 and SIRT1 after transfection was observed by qRT-PCR and Western blot. The target relationship between miR-221 and SIRT1 was confirmed using dual-luciferase reporter assay.The cell viability changes after transfection was measured using cellTiter-blue reagent. The apoptosis rate was detected by flow cytometry.

RESULT

Compared with healthy controls, miR-221 expression significantly increased in bronchial epithelial cells from patients subjects. In contrast, the level of SIRT1 mRNA reduced in the bronchial epithelial cell from asthma patients. In vitro, up-regulation of miR-221 could inhibit the expression of SIRT1 both at mRNA and protein level in BEAS2B cells. A negative correlation between miR-221 and SIRT1 mRNA in samples from patients was confirmed and dual-luciferase reporter assay showed that miR-221 directly binds to the 3'UTR of SIRT1 mRNA. Overexpression of miR-221 or SIRT1 knockdown could inhibit proliferation but induce apoptosis in BEAS2B cells. Moreover, up-regulation of SIRT1 could antagonize miR-221's inhibitory effect.

CONCLUSION

miR-221 may participate in the airway epithelial cells injury in asthma via targeting SIRT1.

Serum SIRT1 Is Associated with Frailty and Adipokines in Older Adults

BACKGROUND

Because frailty is a major health concern among older patients, identifying frailty-related biomarkers will help in the early detection and prevention of frailty. Thus, we aimed to determine the association between circulating levels of silent mating-type information regulation 2 homolog 1 (SIRT1) and frailty.

METHODS

We assessed circulating SIRT1 levels in 16 robust, 74 prefrail, and 40 frail older adults. Frailty was diagnosed based on the Fried phenotype. Circulating cytokine and adipokine (e.g., vaspin, adiponectin, and leptin) levels were assessed. Differences in SIRT1 levels among the three subject groups were compared; correlations of SIRT1 levels with physical function and adipokine and cytokine levels were analyzed.

RESULTS

Serum SIRT1 levels were significantly higher among frail older adults than among robust ones. Older adults with slowness or weight loss had high SIRT1 levels. Serum SIRT1 levels negatively correlated with gait speed, even after adjustment for age and sex; age; and insulin, vaspin, and leptin levels; they correlated negatively with phospholipase A2 levels.

CONCLUSIONS

High SIRT1 levels were observed in frail elderly patients and were correlated with decreased physical function. Insulin and adipokine levels might be the link between SIRT1 and frailty, whereas inflammation may not be involved in this process.

Detection of Sirtuin-1 protein expression in peripheral blood leukocytes in dogs

Sirtuin-1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD⁺)-dependent histone deacetylase with a large number of protein substrates. It has attracted a lot of attention in association with extending lifespan. The objective of this study was to enable the evaluation of SIRT1 expression in peripheral blood mononuclear cells (PBMCs) from dogs by flow cytometry. Three transcript variants were amplified from PBMCs by reverse transcription PCR and the nucleotide sequences were analyzed. On the basis of deduced amino acid sequence, a monoclonal antibody against human SIRT1, 1F3, was selected to detect canine SIRT1. Canine SIRT1 in peripheral blood mononuclear cells was successfully detected by western blotting using this antibody. Intracellular canine SIRT1 was also detected in permeabilized 293T cells transfected with a canine SIRT1 expression plasmid by flow cytometry using this antibody. SIRT1 was detected in all leukocyte subsets including lymphocytes, granulocytes and monocytes. The expression level was markedly different among individual dogs. These results indicated that the method applied in this study is useful for evaluating canine SIRT1 levels in PBMCs from dogs.

TIM4-TIM1 interaction modulates Th2 pattern inflammation through enhancing SIRT1 expression

Skewed T helper 2 (Th2)-cell polarization plays a critical role in the pathogenesis of allergic inflammations; however, the underlying mechanisms require further elucidation. The aim of the present study was to investigate the mechanisms through which the interaction between T-cell immunoglobulin and mucin domain (TIM)4 and TIM1 regulates the expression of silent information regulator 1 (SIRT1) in Th2 cells, and the role of SIRT1 in Th2-cell polarization during nasal allergic inflammation. The results demonstrated that TIM4 expression by splenic dendritic cells was increased in mice with allergic rhinitis, and the TIM4̸TIM1 interaction promoted CD4⁺ T cells to express SIRT1 during allergic inflammation via enhancing phosphoinositide 3-kinase/Akt phosphorylation. SIRT1 then facilitated CD4⁺ T-cell proliferation through downregulating the expression of Fas ligand, caspase-3 and p53 in mice with nasal allergic inflammation. In conclusion, the interaction of TIM4̸TIM1 was found to promote Th2-cell proliferation through enhancing SIRT1 expression in mice with nasal allergic rhinitis.

Decreased Serum Sirtuin-1 in COPD

Background

The protein deacetylase sirtuin-1 (SIRT1) is an antiaging molecule that is decreased in the lung in patients with COPD. Recently, SIRT1 was reported to be detectable in serum, but serum SIRT1 (s120S) levels have not yet been reported in patients with COPD.

Methods

Serum SIRT1 protein of all samples was measured by Western blot, and the SIRT1 protein band densities were calculated and compared with clinical parameters.

Results

Several molecular sizes of SIRT1, including 120 kDa (actual size) and fragments (102 and 75 kDa) were quantified by Western blot. Among them, only the 120-kDa s120S was significantly decreased in patients with COPD compared with the control subjects without COPD (s120S ratio in healthy subjects = 0.90 ± 0.34 vs those with COPD = 0.68 ± 0.24; P = .014) and was positively correlated with airway obstruction (FEV₁/FVC, r = 0.31; P = .020); its severity measured by FEV₁ % predicted (r = 0.29; P = .029). s120S also showed a positive correlation with BMI (r = 0.36; P = .0077) and diffusing capacity of the lung per unit volume (the carbon monoxide transfer coefficient: K_CO%) (r = 0.32; P = .025). It was also significantly decreased with increasing severity of lung emphysema (r = –0.40; P = .027) and with a clinical history of frequent COPD exacerbations (infrequent vs frequent, 0.76 ± 0.20 vs 0.56 ± 0.26; P = .027). SIRT1 was not detected in supernatant of A549 and primary epithelial cells in normal culture conditions.

Conclusions

s120S was decreased in the patients with COPD, potentially as reflected by the reduced SIRT1 within cells as a result of oxidative stress, and might be a potential biomarker for certain disease characteristics of COPD.