Inhibition of Sirt2 Alleviates Fibroblasts Activation and Pulmonary Fibrosis via Smad2/3 Pathway

SIRT3/6/7: promising therapeutic targets for pulmonary fibrosis

Pulmonary fibrosis is a chronic progressive fibrosing interstitial lung disease of unknown cause, characterized by excessive deposition of extracellular matrix, leading to irreversible decline in lung function and ultimately death due to respiratory failure and multiple complications. The Sirtuin family is a group of nicotinamide adenine dinucleotide (NAD+) -dependent histone deacetylases, including SIRT1 to SIRT7. They are involved in various biological processes such as protein synthesis, metabolism, cell stress, inflammation, aging and fibrosis through deacetylation. This article reviews the complex molecular mechanisms of the poorly studied SIRT3, SIRT6, and SIRT7 subtypes in lung fibrosis and the latest research progress in targeting them to treat lung fibrosis.

SIRT2 inhibition attenuates myofibroblast transition through autophagy-mediated ciliogenesis in renal epithelial cells

Myofibroblast transition plays a crucial role in both fibrotic diseases and wound healing. Although SIRT2 regulates fibrosis, its mechanisms of action remain poorly understood. This study aimed to investigate the effects of SIRT2 inhibition on myofibroblast transition in human renal cells under quiescent conditions. HK-2 kidney proximal tubular epithelial cells were starved of serum, resulting in the formation of primary cilia. Transforming growth factor-β (TGF-β) stimulation reduced both the number of ciliated cells and ciliary length. The ciliary defects resulted from a failure in autophagy termination, leading to the accumulation of OFD1, a negative regulator of ciliogenesis, at centriolar satellites. This phenomenon was correlated with the upregulation of fibrosis-related proteins. To elucidate the role of SIRT2 in the autophagy-ciliogenesis-fibrosis axis, cells were treated with AGK2, a specific inhibitor of SIRT2. AGK2 treatment promoted the formation of both autophagosomes and autolysosomes and facilitated OFD1 degradation at the centriolar satellites, resulting in the lengthening of primary cilia. Restoration of primary cilia by AGK2 was associated with the suppression of myofibroblast transition. In conclusion, SIRT2 inhibition attenuates TGF-β-induced fibrosis by promoting autophagy-mediated ciliogenesis. This study highlights SIRT2 as a potential therapeutic target for fibrotic diseases.

Protective Effects of SIRT2 Inhibition on Cardiac Fibrosis

BACKGROUND

A primary factor in the pathogenesis of aging is oxidative stress, with cardiac inflammation and fibrosis being contributed to by increased oxidative stress as organisms age. Oxidative stress enhances the cardiac fibrotic signaling pathway, with reactive oxygen species inducing cardiac fibrosis through increased expression of the profibrotic factor transforming growth factor-beta 1 (TGF-β1). Furthermore, Wnt/β-catenin signaling pathway is implicated in interstitial fibrosis, which is associated with TGF-β. Sirtuin 2 (SIRT2) is expressed in heart tissue, with protective effects in pathological cardiac hypertrophy. We aimed to investigate the mechanisms of cardiac fibrosis in D-Galactose (D-Gal)-induced accelerated aging, focusing on TGF-β1, β-catenin, and SIRT2.

METHODS

A total of 30 young male Sprague-Dawley rats were randomly divided into 4 groups: control group, D-Gal group, D-Gal + 4% dimethyl sulfoxide (DMSO) group, and D-Gal + the SIRT2 inhibitor (AGK2) group. After 10 weeks, the rats were sacrificed, and their hearts were removed. SIRT2 expression levels were measured by western blot and gene expression levels of TGF-β1 and β-catenin by quantitative real-time polymerase chain reaction.

RESULTS

Transforming growth factor-beta 1 (TGF-β1) mRNA expression in heart tissue was higher in the D-Gal group compared to all other groups. β-catenin mRNA expression was higher in the D-Gal group than in the D-Gal + AGK2 group. SIRT2 protein expression was higher in the D-Gal + DMSO group compared to the control group. Sirtuin 2 expression was lower in the D-Gal + AGK2 group compared to the D-Gal and D-Gal + DMSO groups.

CONCLUSION

Sirtuin 2 inhibition attenuates fibrosis, as evidenced by the downregulation of TGF-β1 and β-catenin. Thus, targeting SIRT2 may represent a potential therapeutic strategy for diseases characterized by cardiac fibrosis in the future.

Proteomics profiling of inflammatory responses to elexacaftor/tezacaftor/ivacaftor in cystic fibrosis

Background

CFTR modulator therapies have positive clinical outcomes, yet chronic inflammation and bacterial infections persist in people with CF (pwCF). How elexacaftor-tezacaftor-ivacaftor (ETI) fails to improve innate immune signaling responsible for bacterial clearance and inflammation resolution remains unknown.

Methods

We used an unbiased proteomics approach to measure the effect of ETI on inflammatory proteins. Plasma from 20 pediatric pwCF and 20 non-CF (NCF) was collected during routine examination and 3 months after ETI initiation. Protein screening was performed with an inflammation panel (Target 96, Olink®). Bioinformatics analysis was used to determine changes in protein expression.

Results

There were significantly fewer pulmonary exacerbations after ETI initiation, along with sustained improvement in lung function and reduced bacterial colonization. Unpaired analysis of CF pre-ETI and NCF resulted in 34 significantly different proteins. Of these, CCL20, MMP-10, EN-RAGE, and AXIN1 had a log2 fold change of 1.2 or more. There was a modest shift in overall CF protein profiles post-ETI toward the NCF cluster. Unpaired analysis of protein differential expression between NCF and CF post-ETI identified a total of 24 proteins significantly impacted by ETI therapy (p-value ≤ 0.05), with only CCL20 having a log2 fold change higher than 1.2. Paired analysis (CF pre- and CF post-ETI) of differential protein expression demonstrated significant expression changes of MMP-10, EN-RAGE, and IL-17A. Pathway analysis identified significantly impacted pathways such as the NF-κB pathway.

Conclusion

This study showed that ETI in a pediatric cohort had a modest effect on several inflammatory proteins with potential as biomarkers. Pathways significantly impacted by ETI can be further studied for future therapies to combat persistent inflammation and dysregulated immunity.

Design, synthesis, and biological evaluation of novel 3-naphthylthiophene derivatives as potent SIRT2 inhibitors for the treatment of myocardial fibrosis

SIRT2 (sirtuin2) is a NAD+-dependent deacetylase implicated in fibrosis and inflammation of the liver, kidney, and heart. In this study, we designed and synthesized a series of 3-naphthylthiophene derivatives and evaluated their inhibitory activity against the SIRT2 enzyme. Among them, Z18 demonstrated outstanding SIRT2 inhibitory activity and selectivity. It significantly inhibited both the proliferation of cardiac fibroblasts (CFs) and the activity and expression of SIRT2 in CFs. Moreover, compound Z18 effectively suppressed TGF-β1-induced increases in α-SMA and CoL-1A1 protein expression, as well as hydroxyproline levels. Pharmacological mechanism tests demonstrated that Z18 inhibited SIRT2, thereby suppressing the TGF-β1-induced autocrine production of TGF-β1 and the phosphorylation of Smad2/3 in CFs. In MTT assays, Z18 exhibited a significant inhibitory effect on the proliferation of CFs induced by TGF-β1. In vivo, Z18 effectively ameliorated TAC- and ISO-induced declines in cardiac function, histopathological morphological changes, and collagen deposition. It also inhibited SIRT2 activity and reduced the expression of α-SMA and p-Smad2/3. In hepatorenal toxicity assays, Z18 exhibited an excellent safety profile. These results support the further development of the selective SIRT2 inhibitor Z18 as a potential lead compound for the treatment of myocardial fibrosis.

Nampt/SIRT2/LDHA pathway-mediated lactate production regulates follicular dysplasia in polycystic ovary syndrome

Decreased nicotinamide adenine dinucleotide (NAD+) content has been shown to contribute to metabolic dysfunction during aging, including polycystic ovary syndrome (PCOS). However, the effect of NAD+ on ovulatory dysfunction in PCOS by regulating glycolysis has not been reported. Based on the observations of granulosa cells (GCs) transcriptome data from the Gene Expression Omnibus (GEO) database, the signal pathways including glycolysis and nicotinate-nicotinamide metabolism were significantly enriched, and most genes of the above pathway like LDHA and SIRT2 were down-regulated in PCOS patients. Therefore, the PCOS rat model was established by combining letrozole with a high-fat diet (HFD), we demonstrate that in vivo supplementation of nicotinamide mononucleotide (NMN) significantly improves the ovulatory dysfunction by facilitating the follicular development, promoting luteal formation, as well the fertility in PCOS rats. Furthermore, target energy metabolomics and transcriptome results showed that NMN supplementation ameliorates the lactate production by activating glycolytic process in the ovary. In vitro, when NAD+ synthesis and SIRT2 expression were inhibited, lactate content in KGN cells was decreased and LDHA expression was significantly inhibited. We confirmed that FK866 can enhance the acetylation of LDHA on 293T cells by Co-immunoprecipitation (Co-IP) assay. We also observed that inhibition of NAD+ synthesis can reduce the activity and increase the apoptosis of KGN cells. Overall, these benefits of NMN were elucidated and the Nampt/SIRT2/LDHA pathway mediated lactate production in granulosa cells played an important role in the improvement of follicular development disorders in PCOS. This study will provide experimental evidence for the clinical application of NMN in the treatment of PCOS in the future.

AGK2, a SIRT2 inhibitor, ameliorates D-galactose-induced liver fibrosis by inhibiting fibrogenic factors

In our study, we aimed to investigate the effect of SIRT2 inhibition on function, fibrosis and inflammation in liver fibrosis induced by D-Galactose (D-Gal) administration. A total of 32 3-month-old Sprague Dawley rats were used in the study. Rats were divided into 4 groups as Control, d-Gal, Solvent+d-Gal, d-Gal+AGK2+Solvent. d-Gal (150 mg/kg/day), AGK-2 (10 µM/bw) as a specific SIRT2 inhibitor, 4%DMSO + PBS as a solvent was applied to the experimental groups and physiological saline was applied to the control group for 10 weeks. All applications were performed subcutaneously. Histological fibrotic changes were studied in the liver tissues by Masson's trichrome staining, hematoxylin and eosin staining and immunohistochemistry and the levels of selected factors were determined by quantitative reverse transcription-polymerase chain reaction, western blot analysis, and immunohistochemical analysis. Biochemical parameters and Paraoxonase levels were determined in the plasma. d-Galactose administration increased AST, AST-ALT Ratio, APRI, SIRT2 protein expression, IL1β, TGF β, β-catenin, Type I collagen, Type III collagen and α-SMA, collagen fiber density and histopathological score. ALT and lipid panels were not changed and paraxonase plasma level was shown to decrease. These effects were largely blocked by the SIRT2 inhibitor AGK2. These findings suggest that SIRT2 inhibition attenuates d-Gal-induced liver injury and that this protection may be due to its antifibrotic and anti-inflammatory activities.

Targeting SIRT2 in Aging-Associated Fibrosis Pathophysiology

Aging is a complex biological process that involves multi-level structural and physiological changes. Aging is a major risk factor for many chronic diseases. The accumulation of senescent cells changes the tissue microenvironment and is closely associated with the occurrence and development of tissue and organ fibrosis. Fibrosis is the result of dysregulated tissue repair response in the development of chronic inflammatory diseases. Recent studies have clearly indicated that SIRT2 is involved in regulating the progression of fibrosis, making it a potential target for anti-fibrotic drugs. SIRT2 is a NAD+ dependent histone deacetylase, shuttling between nucleus and cytoplasm, and is highly expressed in liver, kidney and heart, playing an important role in the occurrence and development of aging and fibrosis. Therefore, we summarized the role of SIRT2 in liver, kidney and cardiac fibrosis during aging.

Marrow mesenchymal stem cell mediates diabetic nephropathy progression via modulation of Smad2/3/WTAP/m6A/ENO1 axis

Diabetic nephropathy (DN) is one of the common microvascular complications in diabetic patients. Marrow mesenchymal stem cells (MSCs) have attracted attention in DN therapy but the underlying mechanism remains unclear. Here, we show that MSC administration alleviates high glucose (HG)-induced human kidney tubular epithelial cell (HK-2 cell) injury and ameliorates renal injury in DN mice. We identify that Smad2/3 is responsible for MSCs-regulated DN progression. The activity of Smad2/3 was predominantly upregulated in HG-induced HK-2 cell and DN mice and suppressed with MSC administration. Activation of Smad2/3 via transforming growth factor-β1 (TGF-β1) administration abrogates the protective effect of MSCs on HG-induced HK-2 cell injury and renal injury of DN mice. Smad2/3 has been reported to interact with methyltransferase of N6-methyladenosine (m6A) complex and we found a methyltransferase, Wilms' tumor 1-associating protein (WTAP), is involved in MSCs-Smad2/3-regulated DN development. Moreover, WTAP overexpression abrogates the improvement of MSCs on HG-induced HK-2 cell injury and renal injury of DN mice. Subsequently, α-enolase (ENO1) is the downstream target of WTAP-mediated m6A modification and contributes to the MSCs-mediated regulation. Collectively, these findings reveal a molecular mechanism in DN progression and indicate that Smad2/3/WTAP/ENO1 may present a target for MSCs-mediated DN therapy.

Epigenetic modification in liver fibrosis: Promising therapeutic direction with significant challenges ahead

Liver fibrosis, characterized by scar tissue formation, can ultimately result in liver failure. It's a major cause of morbidity and mortality globally, often associated with chronic liver diseases like hepatitis or alcoholic and non-alcoholic fatty liver diseases. However, current treatment options are limited, highlighting the urgent need for the development of new therapies. As a reversible regulatory mechanism, epigenetic modification is implicated in many biological processes, including liver fibrosis. Exploring the epigenetic mechanisms involved in liver fibrosis could provide valuable insights into developing new treatments for chronic liver diseases, although the current evidence is still controversial. This review provides a comprehensive summary of the regulatory mechanisms and critical targets of epigenetic modifications, including DNA methylation, histone modification, and RNA modification, in liver fibrotic diseases. The potential cooperation of different epigenetic modifications in promoting fibrogenesis was also highlighted. Finally, available agonists or inhibitors regulating these epigenetic mechanisms and their potential application in preventing liver fibrosis were discussed. In summary, elucidating specific druggable epigenetic targets and developing more selective and specific candidate medicines may represent a promising approach with bright prospects for the treatment of chronic liver diseases.

The role of Sirtuin 2 in liver - An extensive and complex biological process

Liver disease has become one of the main causes of health issue worldwide. Sirtuin (Sirt) 2 is a nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase, and is expressed in multiple organs including liver, which plays important and complex roles by interacting with various substrates. Physiologically, Sirt2 can improve metabolic homeostasis. Pathologically, Sirt2 can alleviate inflammation, endoplasmic reticulum (ER) stress, promote liver regeneration, maintain iron homeostasis, aggravate fibrogenesis and regulate oxidative stress in liver. In liver diseases, Sirt2 can mitigate fatty liver disease (FLD) including non-alcoholic fatty liver disease (NAFLD) and alcoholic fatty liver disease (AFLD), but aggravate hepatitis B (HBV) and liver ischemia-reperfusion injury (LIRI). The role of Sirt2 in liver cancer and aging-related liver diseases, however, has not been fully elucidated. In this review, these biological processes regulated by Sirt2 in liver are summarized, which aims to update the function of Sirt2 in liver and to explore the potential role of Sirt2 as a therapeutic target for liver diseases.

Eupatilin inhibits pulmonary fibrosis by activating Sestrin2/PI3K/Akt/mTOR dependent autophagy pathway

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive chronic inflammatory disease with poor clinical outcomes and ineffective drug treatment options. Eupatilin is a major component extracted from the traditional herbal medicine Artemisia asiatica Nakai. Notably, it was demonstrated to have an anti-fibrosis effect in endometrial fibrosis, vocal fold, and hepatic fibrosis. Its role and mechanism in IPF remain unclear.

METHODS

This study used the TGF-β1-induced human embryonic lung fibroblasts (MRC-5) activation, IPF lung fibroblasts, and bleomycin-induced lung fibrosis mice model. Western blot, immunofluorescence staining, quantitative real time-PCR, hematoxylin and eosin staining, Masson's trichrome staining, and immunohistochemistry were used to evaluate the effects of eupatilin on fibroblast activation, pulmonary fibrosis, and autophagy. The autophagosomes were observed with a transmission electron microscope (TEM). RNA sequencing was used to determine the signaling pathway and key regulator related to autophagy.

RESULTS

Eupatilin significantly decreased the expression of Col1A1, fibronectin, α-SMA, and SQSTM1/p62. In contrast, it increased the expression of LC3B II/I and the number of autophagosomes in TGF-β1 treated MRC-5, IPF lung fibroblasts, and bleomycin-induced lung fibrosis mice model; it also alleviated bleomycin-induced lung fibrosis. The KEGG pathway mapping displayed that PI3K/Akt and Sestrin2 were associated with the enhanced fibrogenic process. Eupatilin suppressed the phosphorylation of PI3K/Akt/mTOR. Autophagy inhibitor 3-methyladenine (3-MA) and Akt activator SC-79 abrogated the anti-fibrotic effect of eupatilin. Sestrin2 expression was also downregulated in TGF-β1 treated lung fibroblasts and lung tissues of the bleomycin-induced pulmonary fibrosis mice model. Furthermore, eupatilin promoted Sestrin2 expression, and the knockdown of Sestrin2 significantly aggravated the degree of fibrosis, increased the phosphorylation of PI3K/Akt/mTOR, and decreased autophagy.

CONCLUSION

These findings indicate that eupatilin ameliorates pulmonary fibrosis through Sestrin2/PI3K/Akt/mTOR-dependent autophagy pathway.

Flavin containing monooxygenase 2 regulates renal tubular cell fibrosis and paracrine secretion via SMURF2 in AKI‑CKD transformation

In the follow‑up of hospitalized patients with acute kidney injury (AKI), it has been observed that 15‑30% of these patients progress to develop chronic kidney disease (CKD). Impaired adaptive repair of the kidneys following AKI is a fundamental pathophysiological mechanism underlying renal fibrosis and the progression to CKD. Deficient repair of proximal tubular epithelial cells is a key factor in the progression from AKI to CKD. However, the molecular mechanisms involved in the regulation of fibrotic factor paracrine secretion by injured tubular cells remain incompletely understood. Transcriptome analysis and an ischemia‑reperfusion injury (IRI) model were used to identify the contribution of flavin‑containing monooxygenase 2 (FMO2) in AKI‑CKD. Lentivirus‑mediated overexpression of FMO2 was performed in mice. Functional experiments were conducted using TGF‑β‑induced tubular cell fibrogenesis and paracrine pro‑fibrotic factor secretion. Expression of FMO2 attenuated kidney injury induced by renal IRI, renal fibrosis, and immune cell infiltration into the kidneys. Overexpression of FMO2 not only effectively blocked TGF secretion in tubular cell fibrogenesis but also inhibited aberrant paracrine activation of pro‑fibrotic factors present in fibroblasts. FMO2 negatively regulated TGF‑β‑mediated SMAD2/3 activation by promoting the expression of SMAD ubiquitination regulatory factor 2 (SMURF2) and its nuclear translocation. During the transition from AKI to CKD, FMO2 modulated tubular cell fibrogenesis and paracrine secretion through SMURF2, thereby affecting the outcome of the disease.

SIRT2 alleviated renal fibrosis by deacetylating SMAD2 and SMAD3 in renal tubular epithelial cells

Transforming growth factor-β (TGF-β) is the primary factor that drives fibrosis in most, if not all, forms of chronic kidney disease. In kidneys that are obstructed, specific deletion of Sirt2 in renal tubule epithelial cells (TEC) has been shown to aggravate renal fibrosis, while renal tubule specific overexpression of Sirt2 has been shown to ameliorate renal fibrosis. Similarly, specific deletion of Sirt2 in hepatocyte aggravated CCl4-induced hepatic fibrosis. In addition, we have demonstrated that SIRT2 overexpression and knockdown restrain and enhance TGF-β-induced fibrotic gene expression, respectively, in TEC. Mechanistically, SIRT2 reduced the phosphorylation, acetylation, and nuclear localization levels of SMAD2 and SMAD3, leading to inhibition of the TGF-β signaling pathway. Further studies have revealed that that SIRT2 was able to directly interact with and deacetylate SMAD2 at lysine 451, promoting its ubiquitination and degradation. Notably, loss of SMAD specific E3 ubiquitin protein ligase 2 abolishes the ubiquitination and degradation of SMAD2 induced by SIRT2 in SMAD2. Regarding SMAD3, we have found that SIRT2 interact with and deacetylates SMAD3 at lysine 341 and 378 only in the presence of TGF-β, thereby reducing its activation. This study provides initial indication of the anti-fibrotic role of SIRT2 in renal tubules and hepatocytes, suggesting its therapeutic potential for fibrosis.

Sirtuin family in autoimmune diseases

In recent years, epigenetic modifications have been widely researched. As humans age, environmental and genetic factors may drive inflammation and immune responses by influencing the epigenome, which can lead to abnormal autoimmune responses in the body. Currently, an increasing number of studies have emphasized the important role of epigenetic modification in the progression of autoimmune diseases. Sirtuins (SIRTs) are class III nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylases and SIRT-mediated deacetylation is an important epigenetic alteration. The SIRT family comprises seven protein members (namely, SIRT1-7). While the catalytic core domain contains amino acid residues that have remained stable throughout the entire evolutionary process, the N- and C-terminal regions are structurally divergent and contribute to differences in subcellular localization, enzymatic activity and substrate specificity. SIRT1 and SIRT2 are localized in the nucleus and cytoplasm. SIRT3, SIRT4, and SIRT5 are mitochondrial, and SIRT6 and SIRT7 are predominantly found in the nucleus. SIRTs are key regulators of various physiological processes such as cellular differentiation, apoptosis, metabolism, ageing, immune response, oxidative stress, and mitochondrial function. We discuss the association between SIRTs and common autoimmune diseases to facilitate the development of more effective therapeutic strategies.

Simiao pill attenuates collagen-induced arthritis and bleomycin-induced pulmonary fibrosis in mice by suppressing the JAK2/STAT3 and TGF-β/Smad2/3 signalling pathway

ETHNOPHAMACOLOGICAL RELEVANCE

Simiao Pill (SM) as a classic prescription of traditional Chinese medicine treatment of damp-heat arthralgia, the earliest from 'Cheng Fan Bian Du ', written by the Qing Dynasty doctor Zhang Bingcheng. Previous studies have shown that SM has obvious curative effect on rheumatoid arthritis, which provides a basis for the application of SM in rheumatoid arthritis related complications.

AIM OF THE STUDY

Interstitial lung disease (ILD), as the most severe complication of rheumatoid arthritis (RA), lacks effective clinical treatments and a corresponding animal model. Simiao pill (SM) is a traditional Chinese medicine prescription extensively used as a complementary and alternative treatment for RA. However, the effect and mechanism of SM on RA-ILD have not yet been reported. This study aimed to investigate an appropriate animal model that can simulate RA-ILD, and the efficacy, safety, and mechanism of SM on RA-ILD.

METHODS

Collagen-induced arthritis (CIA) and bleomycin-induced pulmonary fibrosis model were combined to construct the CIA-BLM model. After the intervention of SM, the protective effects of SM on RA-ILD were determined by detecting the CIA mouse arthritis index (AI), Spleen index, and the extent of pulmonary fibrosis. The joint inflammation and pulmonary fibrosis were detected by immunohistochemistry, H&E staining, safranin- O fast green Sirius red staining, trap staining, and Masson staining. Finally, the mechanism was verified by Western blot and immunohistochemistry.

RESULTS

Our work showed that SM significantly reduced joint swelling, arthritis index, pulmonary fibrosis score, and spleen index in CIA mice. The pathological examination results indicated Si-Miao Pill suppressed inflammation, pulmonary fibrosis, bone erosion, and cartilage degradation of the ankle joint. Besides, SM up-regulated expressions of E-cadherin, whereas down-regulated expressions of α-SMA. Further studies confirmed that SM regulated JAK2/STAT3 and TGF-β/SMAD2/3.

CONCLUSION

SM can not only effectively improve joint inflammation by JAK2/STAT3 Pathway but also inhibit pulmonary fibrosis by TGF-β/SMAD2/3. The fibrosis induced by CIA-BLM model was more stable and obvious than that induced by CIA model alone.

Aspirin alleviates pulmonary fibrosis through PI3K/AKT/mTOR-mediated autophagy pathway

Idiopathic pulmonary fibrosis (IPF) is a chronic and irreversible lung disease with limited therapeutic options. Aspirin can alleviate liver, kidney, and cardiac fibrosis. However, its role in lung fibrosis is unclear. This study aims to investigate the effects of aspirin on lung fibroblast differentiation and pulmonary fibrosis. TGF-β1-induced human embryonic lung fibroblasts, IPF lung fibroblasts, and bleomycin-induced lung fibrosis mouse model were used in this study. The results showed that aspirin significantly decreased the expression of Collagen 1A1, Fibronectin, Alpha-smooth muscle actin, and equestosome1, and increased the ratio of light chain 3 beta II/I and the number of autophagosome in vivo and in vitro; reduced bleomycin-induced lung fibrosis. Aspirin also decreased the ratios of phosphorylated phosphatidylinositol 3 kinase (p-PI3K)/PI3K, protein kinase B (p-AKT)/AKT, and mechanistic target of rapamycin (p-mTOR)/mTOR in vitro. Autophagy inhibitor 3-methyladenine, bafilomycin-A1, and AKT activator SC-79 abrogated the effects of aspirin. These findings indicate that aspirin ameliorates pulmonary fibrosis through a PI3K/AKT/mTOR-dependent autophagy pathway.

Tenovin-1 Ameliorates Renal Fibrosis in High-Fat-Diet-Induced Diabetic Nephropathy via Antioxidant and Anti-Inflammatory Pathways

High-fat diet (HFD)-induced obesity has been involved in the development of diabetic nephropathy (DN). Tenovin-1, a potent selective SIRT1/2 inhibitor, regulates various target proteins. The present study evaluated the protective effect of Tenovin-1 against renal fibrosis in HFD-induced Zucker diabetic fatty (ZDF) rats. Rats were fed a normal chow diet or HFD. Tenovin-1 (45 mg/kg) administered to HFD-fed rats decreased inflammatory cytokine expression in the serum of the rats. The antioxidant status and oxidative damage to lipids or DNA were significantly restored by Tenovin-1. Additionally, Tenovin-1 reduced the levels of blood urea nitrogen (BUN), serum creatinine (sCr), microalbumin, and urinary protein-based biomarkers in the urine of HFD-fed rats. The abnormal architecture of the kidney and pancreas was restored by Tenovin-1 administration. Tenovin-1 also reduced apoptosis in the kidneys of the HFD-fed rats and HG-treated NRK-52E cells. It significantly lowered the levels of ECM proteins in the kidneys of HFD-fed rats and HG-treated NRK-52E cells. Additionally, Tenovin-1 markedly reduced claudin-1, SIRT1, and SIRT2, but increased SIRT3 and SIRT4 in HFD-fed rats and NRK-52E cells treated with HG. Furthermore, Tenovin-1 altered epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor-β (PDGFR-β), and signal transducer and activator of transcription 3 (STAT3) levels in the kidneys of HFD-fed rats. Conclusively, this study shows that Tenovin-1 can be a potential candidate drug for the treatment of HFD-induced renal fibrosis, in vivo and in vitro models.

Specific epigenetic regulators serve as potential therapeutic targets in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF), a disorder observed mostly in older human beings, is characterised by chronic and progressive lung scarring leading to an irreversible decline in lung function. This health condition has a dismal prognosis and the currently available drugs only delay but fail to reverse the progression of lung damage. Consequently, it becomes imperative to discover improved therapeutic compounds and their cellular targets to cure IPF. In this regard, a number of recent studies have targeted the epigenetic regulation by histone deacetylases (HDACs) to develop and categorise antifibrotic drugs for lungs. Therefore, this review focuses on how aberrant expression or activity of Classes I, II and III HDACs alter TGF-β signalling to promote events such as epithelial-mesenchymal transition, differentiation of activated fibroblasts into myofibroblasts, and excess deposition of the extracellular matrix to propel lung fibrosis. Further, this study describes how certain chemical compounds or dietary changes modulate dysregulated HDACs to attenuate five faulty TGF-β-dependent profibrotic processes, both in animal models and cell lines replicating IPF, thereby identifying promising means to treat this lung disorder.

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.