Astaxanthin ameliorates lung fibrosis in vivo and in vitro by preventing transdifferentiation, inhibiting proliferation, and promoting apoptosis of activated cells

Astaxanthin attenuates cigarette smoke-induced small airway remodeling via the AKT1 signaling pathway

BACKGROUND

Astaxanthin (AXT) is a keto-carotenoid with a variety of biological functions, including antioxidant and antifibrotic effects. Small airway remodeling is the main pathology of chronic obstructive pulmonary disease (COPD) and is caused by epithelial-to-mesenchymal transition (EMT) and fibroblast differentiation and proliferation. Effective therapies are still lacking. This study aimed to investigate the role of AXT in small airway remodeling in COPD and its underlying mechanisms.

METHODS

First, the model of COPD mice was established by cigarette smoke (CS) exposure combined with intraperitoneal injection of cigarette smoke extract (CSE). The effects of AXT on the morphology of CS combined with CSE -induced emphysema, EMT, and small airway remodeling by using Hematoxylin-eosin (H&E) staining, immunohistochemical staining, and western blot. In addition, in vitro experiments, the effects of AXT on CSE induced-EMT and fibroblast function were further explored. Next, to explore the specific mechanisms underlying the protective effects of AXT in COPD, potential targets of AXT in COPD were analyzed using network pharmacology. Finally, the possible mechanism was verified through molecular docking and in vitro experiments.

RESULTS

AXT alleviated pulmonary emphysema, EMT, and small airway remodeling in a CS combined with CSE -induced mouse model. In addition, AXT inhibited the EMT process in airway cells and the differentiation and proliferation of fibroblasts. Mechanistically, AXT inhibited myofibroblast activation by directly binding to and suppressing the phosphorylation of AKT1. Therefore, our results show that AXT protects against small airway remodeling by inhibiting AKT1.

CONCLUSIONS

The present study identified and illustrated a new food function of AXT, indicating that AXT could be used in the therapy of COPD-induced small airway remodeling.

Effects of Anti-Fibrotic Drugs on Transcriptome of Peripheral Blood Mononuclear Cells in Idiopathic Pulmonary Fibrosis

Two anti-fibrotic drugs, pirfenidone (PFD) and nintedanib (NTD), are currently used to treat idiopathic pulmonary fibrosis (IPF). Peripheral blood mononuclear cells (PBMCs) are immunocompetent cells that could orchestrate cell-cell interactions associated with IPF pathogenesis. We employed RNA sequencing to examine the transcriptome signature in the bulk PBMCs of patients with IPF and the effects of anti-fibrotic drugs on these signatures. Differentially expressed genes (DEGs) between "patients with IPF and healthy controls" and "before and after anti-fibrotic treatment" were analyzed. Enrichment analysis suggested that fatty acid elongation interferes with TGF-β/Smad signaling and the production of oxidative stress since treatment with NTD upregulates the fatty acid elongation enzymes ELOVL6. Treatment with PFD downregulates COL1A1, which produces wound-healing collagens because activated monocyte-derived macrophages participate in the production of collagen, type I, and alpha 1 during tissue damage. Plasminogen activator inhibitor-1 (PAI-1) regulates wound healing by inhibiting plasmin-mediated matrix metalloproteinase activation, and the inhibition of PAI-1 activity attenuates lung fibrosis. DEG analysis suggested that both the PFD and NTD upregulate SERPINE1, which regulates PAI-1 activity. This study embraces a novel approach by using RNA sequencing to examine PBMCs in IPF, potentially revealing systemic biomarkers or pathways that could be targeted for therapy.

Protective effects of Qing-Re-Huo-Xue formula on bleomycin-induced pulmonary fibrosis through the p53/IGFBP3 pathway

Background

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive fibrosing lung disease with high mortality. Inflammation and epithelial mesenchymal transformation (EMT) may play an important role in the occurrence and development of IPF. Qing-Re-Huo-Xue formula (QRHXF) has been used clinically by our team for half a century and has obvious therapeutic effects on lung disease. Nevertheless, the role and mechanism of QRHXF in the treatment of IPF have never been studied.

Methods

A mouse pulmonary fibrosis model was established by intratracheal injection of BLM. The effects of QRHXF on the treatment of pulmonary fibrosis were studied by pulmonary function testing, imaging examination, pathological staining, transmission electron microscopy (TEM) observation and mRNA expression. Tandem mass tag (TMT)-based quantitative proteomics was carried out to analyse the lung protein expression profiles between the control (CTL), bleomycin (BLM) and QRHXF (BLM + QRHXF) groups. Immunohistochemistry and qRT-PCR were used to verify the possible existence of drug target proteins and signalling pathways.

Results

The results of pulmonary function, lung pathology and imaging examinations showed that QRHXF could significantly alleviate BLM-induced pulmonary fibrosis in vivo. Additionally, inflammatory cell infiltration and EMT were markedly reduced in BLM-induced PF mice administered QRHXF. Proteomics detected a total of 35 proteins, of which 17 were upregulated and 18 were downregulated. A total of 19 differentially expressed proteins (DEPs) overlapped between the BLM versus CTL groups and the BLM + QRHXF versus BLM groups. The expression of p53 and IGFBP3 was reversed in the QRHXF intervention group, which was verified by immunohistochemistry and qRT-PCR.

Conclusions

QRHXF attenuated BLM-induced pulmonary fibrosis, and regulation of the p53/IGFBP3 pathway might be associated with its efficacy, which holds promise as a novel treatment strategy for pulmonary fibrosis patients.

Graphical Abstract

Astaxanthin: A promising therapeutic agent for organ fibrosis

Fibrosis is the end-stage pathological manifestation of many chronic diseases. Infiltration of inflammatory cells and activation of myofibroblasts are the most prominent features of fibrosis, with excessive deposition of extracellular matrix (ECM) in tissues leading to organ tissue damage, which eventually progresses to organ failure and leads to high mortality rates. At present, a large number of studies have been conducted on tissue fibrosis, and the pathological mechanism of fibrosis development has generally been recognized. However, the prevention and treatment of fibrosis is still an unsolved problem, and a shortage of drugs that can be used in the clinic persists. Astaxanthin (ASTX), a carotenoid, is widely known for its strong antioxidant capacity. ASTX also has other biological properties, such as anti-inflammatory, antiaging and anticancer properties. Recently, many papers have reported that ASTX inhibits the occurrence and development of fibrosis by regulating signaling molecular pathways, such as transforming growth factor-β/small mother against decapentaplegic protein (TGF-β1/Smad), sirtuin 1 (SIRT1), nuclear factor kappa-B (NF-κB), microRNA, nuclear factor-E2-related factor 2/antioxidant response element (Nrf 2/ARE) and reactive oxygen species (ROS) pathways. By targeting these molecular signaling pathways, ASTX may become a potential drug for the treatment of fibrotic diseases. In this review, we summarize the therapeutic effects of ASTX on organ fibrosis and its underlying mechanisms of action. By reviewing the results from in vitro and in vivo studies, we analyzed the therapeutic prospects of ASTX for various fibrotic diseases and provided insights into and strategies for exploring new drugs for the treatment of fibrosis.

Untapping the protective role of carotenoids against respiratory diseases

BACKGROUND

Recent studies revealed a substantial role of carotenoids to treat respiratory diseases. This review aimed to give an updated overview of the investigational evidence on the preventive properties of carotenoids against respiratory diseases both in vitro and in vivo along with their pathophysiology and mechanisms of action.

HYPOTHESIS

Carotenoids as a potential therapeutic class of bioactive compounds to treat respiratory diseases.

RESULTS

Carotenoids such as β-carotene, lycopene, crocin, bixin, lutein, and astaxanthin show beneficial effects against chronic lung diseases (e.g., asthma, emphysema, fibrosis, COPD, acute lung injury, and lung cancer). Moreover, in vitro and in vivo studies also supported the preventive role of carotenoids. These carotenoids showed a beneficial role by activation of the NRF2/HO-1 pathway and inhibition of the NF-кB, MAPK, JAK/STAT-3, and PI3K/AKT pathways. Additionally, epidemiological studies also showed that dietary intake of carotenoids lowers the risk of lung diseases.

CONCLUSION

Carotenoids may be used as drugs or can be given in combination with other drugs to prevent and treat respiratory diseases. Although in vitro and in vivo results are encouraging, further well-conducted randomized clinical trials are required to approve carotenoids as drug candidates.

Health benefits of astaxanthin against age-related diseases of multiple organs: A comprehensive review

Age-related diseases are associated with increased morbidity in the past few decades and the cost associated with the treatment of these age-related diseases exerts a substantial impact on social and health care expenditure. Anti-aging strategies aim to mitigate, delay and reverse aging-associated diseases, thereby improving quality of life and reducing the burden of age-related pathologies. The natural dietary antioxidant supplementation offers substantial pharmacological and therapeutic effects against various disease conditions. Astaxanthin is one such natural carotenoid with superior antioxidant activity than other carotenoids, as well as well as vitamins C and E, and additionally, it is known to exhibit a plethora of pharmacological effects. The present review summarizes the protective molecular mechanisms of actions of astaxanthin on age-related diseases of multiple organs such as Neurodegenerative diseases [Alzheimer's disease (AD), Parkinson's disease (PD), Stroke, Multiple Sclerosis (MS), Amyotrophic lateral sclerosis (ALS), and Status Epilepticus (SE)], Bone Related Diseases [Osteoarthritis (OA) and Osteoporosis], Cancers [Colon cancer, Prostate cancer, Breast cancer, and Lung Cancer], Cardiovascular disorders [Hypertension, Atherosclerosis and Myocardial infarction (MI)], Diabetes associated complications [Diabetic nephropathy (DN), Diabetic neuropathy, and Diabetic retinopathy (DR)], Eye disorders [Age related macular degeneration (AMD), Dry eye disease (DED), Cataract and Uveitis], Gastric Disorders [Gastritis, Colitis, and Functional dyspepsia], Kidney Disorders [Nephrolithiasis, Renal fibrosis, Renal Ischemia reperfusion (RIR), Acute kidney injury (AKI), and hyperuricemia], Liver Diseases [Nonalcoholic fatty liver disease (NAFLD), Alcoholic Liver Disease (AFLD), Liver fibrosis, and Hepatic Ischemia-Reperfusion (IR) Injury], Pulmonary Disorders [Pulmonary Fibrosis, Acute Lung injury (ALI), and Chronic obstructive pulmonary disease (COPD)], Muscle disorders (skeletal muscle atrophy), Skin diseases [Atopic dermatitis (ATD), Skin Photoaging, and Wound healing]. We have also briefly discussed astaxanthin's protective effects on reproductive health.

Actin Alpha 2 Downregulation Inhibits Neural Stem Cell Proliferation and Differentiation into Neurons through Canonical Wnt/β-Catenin Signaling Pathway

Our previous study has shown that actin alpha 2 (ACTA2) is expressed in NSC and ACTA2 downregulation inhibits NSC migration by increasing RhoA expression and decreasing the expression of Rac1 to curb actin filament polymerization. Given that proliferation and differentiation are the two main characteristics of NSC, the role of ACTA2 downregulation in the proliferation and differentiation of NSC remains elusive. Here, the results demonstrated that ACTA2 downregulation using ACTA2 siRNA held the potential of inhibiting NSC proliferation using cell counting kit-8 (CCK8) and immunostaining. Then, our data illustrated that ACTA2 downregulation attenuated NSC differentiation into neurons, while directing NSC into astrocytes and oligodendrocytes using immunostaining and immunoblotting. Thereafter, the results revealed that the canonical Wnt/β-catenin pathway was involved in the effect of ACTA2 downregulation on the proliferation and differentiation of NSC through upregulating p-β-catenin and decreasing β-catenin due to inactivating GSK-3β, while this effect could be partially abolished with administration of CHIR99012, a GSK-3 inhibitor. Collectively, these results indicate that ACTA2 downregulation inhibits NSC proliferation and differentiation into neurons through inactivation of the canonical Wnt/β-catenin pathway. The aim of the present study is to elucidate the role of ACTA2 in proliferation and differentiation of NSC and to provide an intervention target for promoting NSC proliferation and properly directing NSC differentiation.

Role of nuclear factor-kappa B in bleomycin induced pulmonary fibrosis and the probable alleviating role of ginsenoside: histological, immunohistochemical, and biochemical study

Bleomycin (BLM) is one of anti-cancerous drugs. One of its limitation is the development of pulmonary fibrosis during therapy So, we proposed to examine the outcome of BLM take on the light and electron microscopic design of rat lung. Along with, assessment the probable protecting role of ginsenoside on BLM induced pulmonary changes. In this study, thirty adult male albino rats were comprised and were classified to four clusters; Negative & positive control group, BLM treated group and BLM& ginsenoside treated group. The lung was treated for histological and immunohistochemical (anti-p65) studies. Light microscopic examination of H&E stained sections of BLM treated group showed huge distortion of the lung building. Mallory trichrome stain of this group showed evident deposition of collagen fibers in the markedly thickened interalveolar septa and around intrapulmonary bronchi, bronchioles and blood vessels. Moreover, strong positive staining for nuclear factor (NF)-κB in the wall of bronchiole as well as the thickened interalveolar septa were observed. Ultrastructural inspection of lung of this group revealed muddled lung planning. Marked improvement of the lung structure and marked reduction in NF-κB immunoexpression was appeared in BLM and ginsenoside treated group. So, we concluded that co-administration of ginsenoside with BLM significantly enhanced the histological and morphometric image of the lung.

Carotenoids: Therapeutic Strategy in the Battle against Viral Emerging Diseases, COVID-19: An Overview

Carotenoids, a group of phytochemicals, are naturally found in the Plant kingdom, particularly in fruits, vegetables, and algae. There are more than 600 types of carotenoids, some of which are thought to prevent disease, mainly through their antioxidant properties. Carotenoids exhibit several biological and pharmaceutical benefits, such as anti-inflammatory, anti-cancer, and immunity booster properties, particularly as some carotenoids can be converted into vitamin A in the body. However, humans cannot synthesize carotenoids and need to obtain them from their diets or via supplementation. The emerging zoonotic virus severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19), originated in bats, and was transmitted to humans. COVID-19 continues to cause devastating international health problems worldwide. Therefore, natural preventive therapeutic strategies from bioactive compounds, such as carotenoids, should be appraised for strengthening physiological functions against emerging viruses. This review summarizes the most important carotenoids for human health and enhancing immunity, and their potential role in COVID-19 and its related symptoms. In conclusion, promising roles of carotenoids as treatments against emerging disease and related symptoms are highlighted, most of which have been heavily premeditated in studies conducted on several viral infections, including COVID-19. Further in vitro and in vivo research is required before carotenoids can be considered as potent drugs against such emerging diseases.

Comparison of Different Methods for Extracting the Astaxanthin from Haematococcus pluvialis: Chemical Composition and Biological Activity

In this study, the impact of different cell disruption techniques (high-pressure micro fluidization (HPMF), ionic liquids (ILs), multi-enzyme (ME), and hydrochloric acid (HCl)) on the chemical composition and biological activity of astaxanthin (AST) obtained from Haematococcus pluvialis was investigated. Results indicated that all cell disruption techniques had a significant effect on AST composition, which were confirmed by TLC and UPC² analysis. AST recovery from HCl (HCl-AST) and ILs (ILs-AST) cell disruption techniques was dominant by free and monoesters AST, while AST recovery from HPMF (HPMF-AST) and ME (ME-AST) cell disruption techniques was composed of monoesters, diesters, and free AST. Further biological activity analysis displayed that HCl-AST showed the highest ABTS and DPPH activity, while ILs-AST showed better results against the ORAC assay. Additionally, ILs-AST exhibits a stronger anti-proliferation of HepG2 cells in a dose-dependent manner, which was ascribed to AST-induced ROS in to inhibit the proliferative of cancer cells.

Epigenetic immunomodulatory effect of eugenol and astaxanthin on doxorubicin cytotoxicity in hormonal positive breast Cancer cells

BACKGROUND

Hormonal receptor positive (HR+) breast cancer is the most commonly diagnosed molecular subtype of breast cancer; which showed good response to doxorubicin (DOX)-based chemotherapy. Eugenol (EUG) and astaxanthin (AST) are natural compounds with proved epigenetic and immunomodulatory effects in several cancer cell lines. This study has been initiated to investigate the molecular mechanism (s) whereby EUG and AST could enhance DOX cytotoxicity in MCF7 cells.

METHODS

Cytotoxic activity of DOX alone and combined with either 1 mM EUG or 40 μM AST was performed using sulphorhodamine-B assay in MCF7 cells. Global histones acetylation and some immunological markers were investigated using ELISA, western blotting and quantitative RT-PCR techniques. Functional assay of multidrug resistance was performed using rhodamine 123 and Hoechst 3342 dyes. Flow cytometry with annexin V and propidium iodide were used to assess the change in cell cycle and apoptosis along with the expression of some differentiation, apoptosis and autophagy proteins.

RESULTS

DOX alone resulted in concentration-dependent cytotoxicity with IC50 of 0.5 μM. Both EUG and AST significantly increased DOX cytotoxicity which is manifested as a significant decrease in DOX IC50 from 0.5 μM to 0.088 μM with EUG and to 0.06 μM with AST. Combinations of DOX with 1 mM EUG or 40 μM AST significantly increased the level of histones acetylation and histone acetyl transferase expression, while reduced the expression of aromatase and epidermal growth factor receptor (EGFR) when compared with 0.25 μM DOX alone. Also both combinations showed higher uptake of rhodamine but lower of Hoechst stains, along with increased the percentage of caspase 3, and decreased the expression of CK7 and LC3BI/II ratio. EUG combination induced IFγ but reduced TNFα causing shifting of cells from G2/M to S and G0/ G1 phases. Combination of DOX with EUG induced apoptosis through the higher BAX/ BCl2 ratio, while with AST was through the increase in caspase 8 expressions.

CONCLUSION

EUG and AST potentiated the anticancer activity of DOX through epigenetic histones acetylation along with the immunonomodulation of different apoptotic approaches in MCF7 cells.

p53: A Key Protein That Regulates Pulmonary Fibrosis

Pulmonary fibrosis is a progressively aggravating lethal disease that is a serious public health concern. Although the incidence of this disease is increasing, there is a lack of effective therapies. In recent years, the pathogenesis of pulmonary fibrosis has become a research hotspot. p53 is a tumor suppressor gene with crucial roles in cell cycle, apoptosis, tumorigenesis, and malignant transformation. Previous studies on p53 have predominantly focused on its role in neoplastic disease. Following in-depth investigation, several studies have linked it to pulmonary fibrosis. This review covers the association between p53 and pulmonary fibrosis, with the aim of providing novel ideas to improve the clinical diagnosis, treatment, and prognosis of pulmonary fibrosis.

The Promising Effects of Astaxanthin on Lung Diseases

Astaxanthin (ASX) is a naturally occurring xanthophyll carotenoid. Both in vitro and in vivo studies have shown that it is a potent antioxidant with anti-inflammatory properties. Lung cancer is the leading cause of cancer death worldwide, whereas other lung diseases such as chronic obstructive pulmonary disease, emphysema, and asthma are of high prevalence. In the past decade, mounting evidence has suggested a protective role for ASX against lung diseases. This article reviews the potential role of ASX in protecting against lung diseases, including lung cancer. It also summarizes the underlying molecular mechanisms by which ASX protects against pulmonary diseases, including regulating the nuclear factor erythroid 2-related factor/heme oxygenase-1 pathway, NF-κB signaling, mitogen-activated protein kinase signaling, Janus kinase-signal transducers and activators of transcription-3 signaling, the phosphoinositide 3-kinase/Akt pathway, and modulating immune response. Several future directions are proposed in this review. However, most in vitro and in vivo studies have used ASX at concentrations that are not achievable by humans. Also, no clinical trials have been conducted and/or reported. Thus, preclinical studies with ASX treatment within physiological concentrations as well as human studies are required to examine the health benefits of ASX with respect to lung diseases.

Insights into the Role of Bioactive Food Ingredients and the Microbiome in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic disease mainly associated with aging and, to date, its causes are still largely unknown. It has been shown that dietary habits can accelerate or delay the occurrence of aging-related diseases; however, their potential role in IPF development has been underestimated so far. The present review summarizes the evidence regarding the relationship between diet and IPF in humans, and in animal models of pulmonary fibrosis, in which we discuss the bioactivity of specific dietary food ingredients, including fatty acids, peptides, amino acids, carbohydrates, vitamins, minerals and phytochemicals. Interestingly, many animal studies reveal preventive and therapeutic effects of particular compounds. Furthermore, it has been recently suggested that the lung and gut microbiota could be involved in IPF, a relationship which may be linked to changes in immunological and inflammatory factors. Thus, all the evidence so far puts forward the idea that the gut-lung axis could be modulated by dietary factors, which in turn have an influence on IPF development. Overall, the data reviewed here support the notion of identifying food ingredients with potential benefits in IPF, with the ultimate aim of designing nutritional approaches as an adjuvant therapeutic strategy.

Biotechnological Applications for the Sustainable Use of Marine By-products: In Vitro Antioxidant and Pro-apoptotic Effects of Astaxanthin Extracted with Supercritical CO2 from Parapeneus longirostris

In this study, the carotenoid astaxanthin was obtained by supercritical fluid extraction (SFE) from shrimp by-products (SBP). Its bioactive properties were evaluated in vitro in human normal and cancerous cells lines. The antioxidant activity of the extracted astaxanthin of the SFE fraction (ASTA) was tested in fibroblast cells (HS-68), by inducing oxidative stress and by evaluating the protective effect of the pre-treatment with different levels of ASTA against toxicity. The anti-proliferative activity was evaluated in hepatoma cells (HEP-G2), treated with increased concentrations of ASTA and measuring the effects on vitality and on some biomolecular markers related to oxidative stress, cell cycle, and apoptosis. It was found that pre-treating normal fibroblast cells with ASTA resulted in a marked increase in cell viability in a dose-dependent manner (P < 0.05) attesting its antioxidant power; in cancer cell line, increased concentrations of ASTA caused a time-dose-dependent decrease in the vitality, attesting its anti-proliferative activity (P < 0.05). The increased levels of the protein p-53 and the reduced levels of the proteins c-Jun and c-Fos at higher concentrations of ASTA, as well as, suggest the pro-apoptotic and anti-cancerous effects that this extract has on hepatocellular carcinomas, confirmed also by caspase-3 activation. These findings suggest biotechnological utilisation of marine by-products for nutraceutical and pharmaceutical applications avoiding the employment of organic solvents for extraction.

Interaction network of coexpressed mRNA, miRNA, and lncRNA activated by TGF‑β1 regulates EMT in human pulmonary epithelial cell

Noncoding RNAs (ncRNAs), such as microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), play increasingly important roles in pathological processes involved in disease development. However, whether mRNAs interact with miRNAs and lncRNAs to form an interacting regulatory network in diseases remains unknown. In this study, the interaction of coexpressed mRNAs, miRNAs and lncRNAs during tumor growth factor-β1-activated (TGF-β1) epithelial-mesenchymal transition (EMT) was systematically analyzed in human alveolar epithelial cells. For EMT regulation, 24 mRNAs, 11 miRNAs and 33 lncRNAs were coexpressed, and interacted with one another. The interaction among coexpressed mRNAs, miRNAs and lncRNAs were further analyzed, and the results showed the lack of competing endogenous RNAs (ceRNAs) among them. The mutual regulation may be correlated with other modes, such as histone modification and transcription factor recruitment. However, the possibility of ceRNA existence cannot be ignored because of the generally low abundance of lncRNAs and frequent promiscuity of protein-RNA interactions. Thus, conclusions need further experimental identification and validation. In this context, disrupting many altered disease pathways remains one of the challenges in obtaining effective pathway-based therapy. The reason being that one specific mRNA, miRNA or lncRNA may target multiple genes that are potentially implicated in a disease. Nevertheless, the results of the present study provide basic mechanistic information, possible biomarkers and novel treatment strategies for diseases, particularly pulmonary tumor and fibrosis.

Astaxanthin alleviated acute lung injury by inhibiting oxidative/nitrative stress and the inflammatory response in mice

The purpose of the present study was to assess the effect of astaxanthin (ASX) treatment on the acute lung injury (ALI) induced by cecal ligation and puncture (CLP) in mice. Mice were randomly allocated into the following groups: (1) the saline control group, in which mice were given saline before sham operation; (2) the ASX control group, in which mice received ASX before sham operation; (3) the ALI group, in which mice were given saline before CLP operation; and (4) the ALI+ASX group, in which mice received ASX before CLP operation. ASX was dissolved in olive oil and administrated by oral gavage for 14days consecutively before the CLP or sham operation. In experiment 1, Kaplan-Meier survival analysis was conducted for 72h after CLP. In experiment 2, blood, bronchoalveolar lavage fluid (BALF) and lung tissues were collected at 24h after the CLP or sham operation to determine the severity of lung injury. The results showed that ASX treatment could significantly decrease the CLP-induced mortality rate in mice. Meanwhile, ASX treatment significantly attenuated CLP-induced lung histopathological injury, inflammatory infiltration, total protein and albumin concentration, and total cell and neutrophil counts in the BALF. Furthermore, ASX treatment alleviated oxidative/nitrative stress, inflammation levels and pulmonary apoptosis in lung tissues. In addition, ASX treatment markedly down-regulated the expression of inducible nitric oxide synthase (i-NOS), nitrotyrosine (NT) and nuclear factor-kappa B (NF-Κb) P65 in the lung tissues compared with that in the ALI group. Astaxanthin treatment had markedly protective effect against ALI in mice, and the potential mechanism is associated with its ability to inhibit the inflammatory response, oxidative/nitrative stress, and pulmonary apoptosis, as well as down-regulate NF-κB P65 expression.

Astaxanthin supplementation attenuates immobilization-induced skeletal muscle fibrosis via suppression of oxidative stress

Immobilization induces skeletal muscle fibrosis characterized by increasing collagen synthesis in the perimysium and endomysium. Transforming growth factor-β1 (TGF-β1) is associated with this lesion via promoting differentiation of fibroblasts into myofibroblasts. In addition, reactive oxygen species (ROS) are shown to mediate TGF-β1-induced fibrosis in tissues. These reports suggest the importance of ROS reduction for attenuating skeletal muscle fibrosis. Astaxanthin, a powerful antioxidant, has been shown to reduce ROS production in disused muscle. Therefore, we investigated the effects of astaxanthin supplementation on muscle fibrosis under immobilization. In the present study, immobilization increased the collagen fiber area, the expression levels of TGF-β1, α-smooth muscle actin, and superoxide dismutase-1 protein and ROS production. However, these changes induced by immobilization were attenuated by astaxanthin supplementation. These results indicate the effectiveness of astaxanthin supplementation on skeletal muscle fibrosis induced by ankle joint immobilization.

Effect of astaxanthin on cutaneous wound healing

Wound healing consists of a complex series of convoluted processes which involve renewal of the skin after injury. ROS are involved in all phases of wound healing. A balance between oxidative and antioxidative forces is necessary for a favorable healing outcome. Astaxanthin, a member of the xanthophyll group, is considered a powerful antioxidant. In this study, we investigated the effect of topical astaxanthin on cutaneous wound healing. Full-thickness dermal wounds were created in 36 healthy female mice, which were divided into a control group and a group receiving 78.9 µM topical astaxanthin treatment twice daily for 15 days. Astaxanthin-treated wounds showed noticeable contraction by day 3 of treatment and complete wound closure by day 9, whereas the wounds of control mice revealed only partial epithelialization and still carried scabs. Wound healing biological markers including Col1A1 and bFGF were significantly increased in the astaxanthin-treated group since day 1. Interestingly, the oxidative stress marker iNOS showed a significantly lower expression in the study. The results indicate that astaxanthin is an effective compound for accelerating wound healing.

miR-30a as Potential Therapeutics by Targeting TET1 through Regulation of Drp-1 Promoter Hydroxymethylation in Idiopathic Pulmonary Fibrosis

Several recent studies have indicated that miR-30a plays critical roles in various biological processes and diseases. However, the mechanism of miR-30a participation in idiopathic pulmonary fibrosis (IPF) regulation is ambiguous. Our previous study demonstrated that miR-30a may function as a novel therapeutic target for lung fibrosis by blocking mitochondrial fission, which is dependent on dynamin-related protein1 (Drp-1). However, the regulatory mechanism between miR-30a and Drp-1 is yet to be investigated. Additionally, whether miR-30a can act as a potential therapeutic has not been verified in vivo. In this study, the miR-30a expression in IPF patients was evaluated. Computational analysis and a dual-luciferase reporter assay system were used to identify the target gene of miR-30a, and cell transfection was utilized to confirm this relationship. Ten–eleven translocation 1 (TET1) was validated as a direct target of miR-30a, and miR-30a mimic and inhibitor transfection significantly reduced and increased the TET1 protein expression, respectively. Further experimentation verified that the TET1 siRNA interference could inhibit Drp-1 promoter hydroxymethylation. Finally, miR-30a agomir was designed and applied to identify and validate the therapeutic effect of miR-30a in vivo. Our study demonstrated that miR-30a could inhibit TET1 expression through base pairing with complementary sites in the 3′untranslated region to regulate Drp-1 promoter hydroxymethylation. Furthermore, miR-30a could act as a potential therapeutic target for IPF.

Supercritical-Carbon Dioxide Fluid Extract from Chrysanthemum indicum Enhances Anti-Tumor Effect and Reduces Toxicity of Bleomycin in Tumor-Bearing Mice

Bleomycin (BLM), a family of anti-tumor drugs, was reported to exhibit severe side effects limiting its usage in clinical treatment. Therefore, finding adjuvants that enhance the anti-tumor effect and reduce the detrimental effect of BLM is a prerequisite. Chrysanthemum indicum, an edible flower, possesses abundant bioactivities; the supercritical-carbon dioxide fluid extract from flowers and buds of C. indicum (CI_SCFE) have strong anti-inflammatory, anti-oxidant, and lung protective effects. However, the role of CI_SCFE combined with BLM treatment on tumor-bearing mice remains unclear. The present study aimed to investigate the potential synergistic effect and the underlying mechanism of CI_SCFE combined with BLM in the treatment of hepatoma 22 (H22) tumor-bearing mice. The results suggested that the oral administration of CI_SCFE combined with BLM could markedly prolong the life span, attenuate the BLM-induced pulmonary fibrosis, suppress the production of pro-inflammatory cytokines (interleukin-6), tumor necrosis factor-α, activities of myeloperoxidase, and malondiadehyde. Moreover, CI_SCFE combined with BLM promoted the ascites cell apoptosis, the activities of caspases 3 and 8, and up-regulated the protein expression of p53 and down-regulated the transforming growth factor-β1 by activating the gene expression of miR-29b. Taken together, these results indicated that CI_SCFE could enhance the anti-cancer activity of BLM and reduce the BLM-induced pulmonary injury in H22 tumor-bearing mice, rendering it as a potential adjuvant drug with chemotherapy after further investigation in the future.

Astaxanthin attenuates total body irradiation-induced hematopoietic system injury in mice via inhibition of oxidative stress and apoptosis

Background

The hematopoietic system is especially sensitive to total body irradiation (TBI), and myelosuppression is one of the major effects of TBI. Astaxanthin (ATX) is a powerful natural anti-oxidant with low toxicity. In this study, the effect of ATX on hematopoietic system injury after TBI was investigated.

Methods

Flow cytometry was used to detect the proportion of hematopoietic progenitor cells (HPCs) and hematopoietic stem cells (HSCs), the level of intracellular reactive oxygen species (ROS), expression of cytochrome C, cell apoptosis, and NRF2-related proteins. Immunofluorescence staining was used to detect Nrf2 translocation. Western blot analysis was used to evaluate the expression of apoptotic-related proteins. Enzymatic activities assay kits were used to analyze SOD2, CAT, and GPX1 activities.

Results

Compared with the TBI group, ATX can improve radiation-induced skewed differentiation of peripheral blood cells and accelerate hematopoietic self-renewal and regeneration. The radio-protective effect of ATX is probably attributable to the scavenging of ROS and the reduction of cell apoptosis. These changes were associated with increased activation of Nrf2 and downstream anti-oxidative proteins, and regulation of apoptotic-related proteins.

Conclusions

This study suggests that ATX could be used as a potent therapeutic agent to protect the hematopoietic system against TBI-induced bone marrow suppression.

Astaxanthin Ameliorates Hepatic Damage and Oxidative Stress in Carbon Tetrachloride-administered Rats

Background

Astaxanthin is of carotenoids group which possess strong antioxidant properties. The present study was conducted to evaluate the hepatoprotective effects of astaxanthin in carbon tetrachloride (CCl₄)-treated rats.

Materials and Methods

Female Long-Evans rats were administered with CCl₄ orally (1 ml/kg) twice a week for 2 weeks and were treated with astaxanthin (10 mg/kg) every day for 2 weeks. Blood plasma samples were isolated from each group and were analyzed for alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase activities. Oxidative stress parameters such as malondialdehyde (MDA), nitric oxide (NO), and advanced protein oxidation product (APOP) were measured. Several enzyme functions such as myeloperoxidase (MPO), superoxide dismutase (SOD), and catalase (CAT) activities in the plasma and liver tissues were also analyzed. Moreover, inflammation and tissue fibrosis were also confirmed by histological staining of liver tissues.

Results

This investigation revealed that CCl₄ administration in rats increased plasma AST, ALT, and ALP activities which were normalized by astaxanthin treatment. Moreover, CCl₄ administration increased as MDA, NO, and APOP level both in plasma and tissues compared to control rats. Astaxanthin also exhibited a significant reduction of those parameters in CCl₄-administered rats. Astaxanthin treatment also restored the CAT and SOD activities and lowered MPO activity in CCl₄-administered rats. Histological assessment also revealed that the astaxanthin prevented the inflammatory cells infiltration, decreased free iron deposition, and fibrosis in liver of CCl₄-administered rats.

Conclusion

These results suggest that astaxanthin protects liver damage induced by CCl₄ by inhibiting lipid peroxidation and stimulating the cellular antioxidant system.

SUMMARY

Carbon tetrachloride (CCl₄) administration increased oxidative stress-mediated hepatic damage and inflammation in ratsAstaxanthin, a potent antioxidant, prevents oxidative stress and inflammatory cells infiltration in CCl₄-administered ratsAstaxanthin also ameliorated the progression of hepatic fibrosis in CCl₄-administered rats. Abbreviations Used: APOP: Advanced protein oxidation product; AST: Aspartate aminotransferase; ALT: Alanine aminotransferase; ALP: Alkaline phosphatase; CAT: Catalase; CCl4: Carbon tetrachloride; CVD: Cardiovascular disease; HSCs: Hepatic stellate cells; H2O2: Hydrogen peroxide; MDA: Malondialdehyde; MMP2: Matrix metalloproteinase2; MPO: Myeloperoxidase; NF-κB: Nuclear factor kappa B; NO: Nitric oxide; Nrf2: Nuclear factor erythroid 2-related factor 2; ·ONOO-: Peroxynitrate; ROS: Reactive oxygen species; SOD: superoxide dismutase; TCA: Trichloroacetic acid; TBA: Thiobarbituric acid; TGF-1: Transforming growth factor 1, TGF-β: Transforming growth factor-β; TIMP1: Tissue inhibitor of metalloproteinase 1; TNF-α: Tumor necrosis factor-alpha;·CCl3: Trichloromethyl free radical; CCl3O2-: Trichloroperoxyl radical.

Astaxanthin improves cognitive performance in mice following mild traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) produces lasting neurological deficits that plague patients and physicians. To date, there is no effective method to combat the source of this problem. Here, we utilized a mild, closed head TBI model to determine the modulatory effects of a natural dietary compound, astaxanthin (AST). AST is centrally active following oral administration and is neuroprotective in experimental brain ischemia/stroke and subarachnoid hemorrhage (SAH) models. We examined the effects of oral AST on the long-term neurological functional recovery and histological outcomes following moderate TBI in a mice model.

METHODS

Male adult ICR mice were divided into 3 groups: (1) Sham+olive oil vehicle treated, (2) TBI+olive oil vehicle treated, and (3) TBI+AST. The olive oil vehicle or AST were administered via oral gavage at scheduled time points. Closed head brain injury was applied using M.A. Flierl weight-drop method. NSS, Rotarod, ORT, and Y-maze were performed to test the behavioral or neurological outcome. The brain sections from the mice were stained with H&E and cresyl-violet to test the injured lesion volume and neuronal loss. Western blot analysis was performed to investigate the mechanisms of neuronal cell survival and neurological function improvement.

RESULTS

AST administration improved the sensorimotor performance on the Neurological Severity Score (NSS) and rotarod test and enhanced cognitive function recovery in the object recognition test (ORT) and Y-maze test. Moreover, AST treatment reduced the lesion size and neuronal loss in the cortex compared with the vehicle-treated TBI group. AST also restored the levels of brain-derived neurotropic factor (BDNF), growth-associated protein-43 (GAP-43), synapsin, and synaptophysin (SYP) in the cerebral cortex, which indicates the promotion of neuronal survival and plasticity.

CONCLUSION

To the best of our knowledge, this is the first study to demonstrate the protective role and the underlining mechanism of AST in TBI. Based on these neuroprotective actions and considering its longstanding clinical use, AST should be considered for the clinical treatment of TBI.

Histone deacetylase 9 plays a role in the antifibrogenic effect of astaxanthin in hepatic stellate cells

Activation of hepatic stellate cells (HSCs) is critical for liver fibrosis development. Previously, we showed that astaxanthin (ASTX), a xanthophyll carotenoid, has antifibrogenic effects in LX-2 cells, a human HSC cell line. We sought to determine the effect of ASTX on HSC activation, and to identify molecular mediators that are critically involved in the processes. ASTX prevented the activation of mouse primary HSCs, as evidenced by attenuated induction of procollagen type I α1. In human primary HSCs, ASTX also inhibited transforming growth factor β1 (TGFβ1)-induced fibrogenic gene expression. Among 11 classical histone deacetylases (HDACs), difference in HDAC9 mRNA levels between quiescent and activated HSCs was most evident while ASTX significantly decreased the expression of HDAC9 and its transcriptional regulator myocyte enhancer factor 2 (MEF2). ASTX decreased HDAC9 protein as well. In the activated HSCs, ASTX significantly reduced mRNA of HDAC9 and MEF2. Human primary biliary cirrhosis livers showed significantly higher HDAC9 mRNA and protein levels than normal livers, and other liver pathologies also exhibited induced HDAC9 expression. HDAC9 knockdown in LX-2 cells decreased TGFβ1-induced fibrogenic gene expression. In conclusion, ASTX inhibits HSC activation and facilitates HSC inactivation, which is attributable to its inhibitory action on HDAC9 expression.

Astaxanthin prevents pulmonary fibrosis by promoting myofibroblast apoptosis dependent on Drp1-mediated mitochondrial fission

Promotion of myofibroblast apoptosis is a potential therapeutic strategy for pulmonary fibrosis. This study investigated the antifibrotic effect of astaxanthin on the promotion of myofibroblast apoptosis based on dynamin-related protein-1 (Drp1)-mediated mitochondrial fission in vivo and in vitro. Results showed that astaxanthin can inhibit lung parenchymal distortion and collagen deposition, as well as promote myofibroblast apoptosis. Astaxanthin demonstrated pro-apoptotic function in myofibroblasts by contributing to mitochondrial fission, thereby leading to apoptosis by increasing the Drp1 expression and enhancing Drp1 translocation into the mitochondria. Two specific siRNAs were used to demonstrate that Drp1 is necessary to promote astaxanthin-induced mitochondrial fission and apoptosis in myofibroblasts. Drp1-associated genes, such as Bcl-2-associated X protein, cytochrome c, tumour suppressor gene p53 and p53-up-regulated modulator of apoptosis, were highly up-regulated in the astaxanthin group compared with those in the sham group. This study revealed that astaxanthin can prevent pulmonary fibrosis by promoting myofibroblast apoptosis through a Drp1-dependent molecular pathway. Furthermore, astaxanthin provides a potential therapeutic value in pulmonary fibrosis treatment.

Astaxanthin inhibits JAK/STAT-3 signaling to abrogate cell proliferation, invasion and angiogenesis in a hamster model of oral cancer

Identifying agents that inhibit STAT-3, a cytosolic transcription factor involved in the activation of various genes implicated in tumour progression is a promising strategy for cancer chemoprevention. In the present study, we investigated the effect of dietary astaxanthin on JAK-2/STAT-3 signaling in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis model by examining the mRNA and protein expression of JAK/STAT-3 and its target genes. Quantitative RT-PCR, immunoblotting and immunohistochemical analyses revealed that astaxanthin supplementation inhibits key events in JAK/STAT signaling especially STAT-3 phosphorylation and subsequent nuclear translocation of STAT-3. Furthermore, astaxanthin downregulated the expression of STAT-3 target genes involved in cell proliferation, invasion and angiogenesis, and reduced microvascular density, thereby preventing tumour progression. Molecular docking analysis confirmed inhibitory effects of astaxanthin on STAT signaling and angiogenesis. Cell culture experiments with the endothelial cell line ECV304 substantiated the role of astaxanthin in suppressing angiogenesis. Taken together, our data provide substantial evidence that dietary astaxanthin prevents the development and progression of HBP carcinomas through the inhibition of JAK-2/STAT-3 signaling and its downstream events. Thus, astaxanthin that functions as a potent inhibitor of tumour development and progression by targeting JAK/STAT signaling may be an ideal candidate for cancer chemoprevention.

MiRNA-30a inhibits AECs-II apoptosis by blocking mitochondrial fission dependent on Drp-1

Apoptosis of type II alveolar epithelial cells (AECs-II) is a key determinant of initiation and progression of lung fibrosis. However, the mechanism of miR-30a participation in the regulation of AECs-II apoptosis is ambiguous. In this study, we investigated whether miR-30a could block AECs-II apoptosis by repressing mitochondrial fission dependent on dynamin-related protein-1 (Drp-1). The levels of miR-30a in vivo and in vitro were determined through quantitative real-time PCR (qRT-PCR). The inhibition of miR-30a in AECs-II apoptosis, mitochondrial fission and its dependence on Drp-1, and Drp-1 expression and translocation were detected using miR-30a mimic, inhibitor-transfection method (gain- and loss-of-function), or Drp-1 siRNA technology. Results showed that miR-30a decreased in lung fibrosis. Gain- and loss-of-function studies revealed that the up-regulation of miR-30a could decrease AECs-II apoptosis, inhibit mitochondrial fission, and reduce Drp-1 expression and translocation. MiR-30a mimic/inhibitor and Drp-1 siRNA co-transfection showed that miR-30a could inhibit the mitochondrial fission dependent on Drp-1. This study demonstrated that miR-30a inhibited AECs-II apoptosis by repressing the mitochondrial fission dependent on Drp-1, and could function as a novel therapeutic target for lung fibrosis.

Astaxanthin inhibits apoptosis in alveolar epithelial cells type II in vivo and in vitro through the ROS-dependent mitochondrial signalling pathway

Oxidative stress is an important molecular mechanism underlying lung fibrosis. The mitochondrion is a major organelle for oxidative stress in cells. Therefore, blocking the mitochondrial signalling pathway may be the best therapeutic manoeuver to ameliorate lung fibrosis. Astaxanthin (AST) is an excellent antioxidant, but no study has addressed the pathway of AST against pulmonary oxidative stress and free radicals by the mitochondrion-mediated signalling pathway. In this study, we investigated the antioxidative effects of AST against H₂O₂- or bleomycin (BLM)-induced mitochondrial dysfunction and reactive oxygen species (ROS) production in alveolar epithelial cells type II (AECs-II) in vivo and in vitro. Our data show that AST blocks H₂O₂- or BLM-induced ROS generation and dose-dependent apoptosis in AECs-II, as characterized by changes in cell and mitochondria morphology, translocation of apoptotic proteins, inhibition of cytochrome c (Cyt c) release, and the activation of caspase-9, caspase-3, Nrf-2 and other cytoprotective genes. These data suggest that AST inhibits apoptosis in AECs-II cells through the ROS-dependent mitochondrial signalling pathway and may be of potential therapeutic value in lung fibrosis treatment.

Alveolar epithelial cells undergo epithelial-mesenchymal transition in acute interstitial pneumonia: a case report

BACKGROUND

Acute interstitial pneumonia is a rare interstitial lung disease that rapidly progresses to respiratory failure or death. Several studies showed that myofibroblast plays an important role in the evolution of diffuse alveolar damage, which is the typical feature of acute interstitial pneumonia. However, no evidence exists whether alveolar epithelial cells are an additional source of myofibroblasts via epithelial-mesenchymal transition in acute interstitial pneumonia.

CASE PRESENTATION

In this report, we present a case of acute interstitial pneumonia in a previously healthy 28-year-old non-smoking woman. Chest high-resolution computed tomography scan showed bilateral and diffusely ground-glass opacification. The biopsy was performed on the fifth day of her hospitalization, and results showed manifestation of acute exudative phase of diffuse alveolar damage characterized by hyaline membrane formation. On the basis of the preliminary diagnosis of acute interstitial pneumonia, high-dose glucocorticoid was used. However, this drug showed poor clinical response and could improve the patient's symptoms only during the early phase. The patient eventually died of respiratory dysfunction. Histological findings in autopsy were consistent with the late form of acute interstitial pneumonia.

CONCLUSIONS

The results in this study revealed that alveolar epithelial cells underwent epithelial-mesenchymal transition and may be an important origin of myofibroblasts in the progression of acute interstitial pneumonia. Conducting research on the transformation of alveolar epithelial cells into myofibroblasts in the lung tissue of patients with acute interstitial pneumonia may be beneficial for the treatment of this disease. However, to our knowledge, no research has been conducted on this topic.

Protective effect of astaxanthin on liver fibrosis through modulation of TGF-β1 expression and autophagy

Liver fibrosis is a common pathway leading to cirrhosis and a worldwide clinical issue. Astaxanthin is a red carotenoid pigment with antioxidant, anticancer, and anti-inflammatory properties. The aim of this study was to investigate the effect of astaxanthin on liver fibrosis and its potential protective mechanisms. Liver fibrosis was induced in a mouse model using CCL4 (intraperitoneal injection, three times a week for 8 weeks), and astaxanthin was administered everyday at three doses (20, 40, and 80 mg/kg). Pathological results indicated that astaxanthin significantly improved the pathological lesions of liver fibrosis. The levels of alanine aminotransferase aspartate aminotransferase and hydroxyproline were also significantly decreased by astaxanthin. The same results were confirmed in bile duct liagtion, (BDL) model. In addition, astaxanthin inhibited hepatic stellate cells (HSCs) activation and formation of extracellular matrix (ECM) by decreasing the expression of NF-κB and TGF-β1 and maintaining the balance between MMP2 and TIMP1. In addition, astaxanthin reduced energy production in HSCs by downregulating the level of autophagy. These results were simultaneously confirmed in vivo and in vitro. In conclusion, our study showed that 80 mg/kg astaxanthin had a significant protective effect on liver fibrosis by suppressing multiple profibrogenic factors.

Analysing the relationship between lncRNA and protein-coding gene and the role of lncRNA as ceRNA in pulmonary fibrosis

Long non-coding RNAs (lncRNAs) are involved in various pathophysiologic processes and human diseases. However, their dynamics and corresponding functions in pulmonary fibrosis remain poorly understood. In this study, portions of lncRNAs adjacent or homologous to protein-coding genes were determined by searching the UCSC genome bioinformatics database. This was found to be potentially useful for exploring lncRNA functions in disease progression. Previous studies showed that competing endogenous RNA (ceRNA) hypothesis is another method to predict lncRNA function. However, little is known about the function of ceRNA in pulmonary fibrosis. In this study, we selected two differentially expressed lncRNAs MRAK088388 and MRAK081523 to explore their regulatory mechanisms. MRAK088388 and MRAK081523 were analysed as long-intergenic non-coding RNAs (lincRNAs), and identified as orthologues of mouse lncRNAs AK088388 and AK081523, respectively. qRT-PCR and in situ hybridization (ISH) showed that they were significantly up-regulated, and located in the cytoplasm of interstitial lung cells. We also showed that MRAK088388 and N4bp2 had the same miRNA response elements (MREs) for miR-200, miR-429, miR-29, and miR-30, whereas MRAK081523 and Plxna4 had the same MREs for miR-218, miR-141, miR-98, and let-7. Moreover, the expression levels of N4bp2 and Plxna4 significantly increased in fibrotic rats, and were highly correlated with those of MRAK088388 and MRAK081523, respectively. Among their shared miRNAs, miR-29b-3p and let-7i-5p decreased in the model group, and were negatively correlated with the expression of MRAK088388 and MRAK081523, respectively. MRAK088388 and MRAK081523 could regulate N4bp2 and Plxna4 expression by sponging miR-29b-3p and let-7i-5p, respectively, and possessed regulatory functions as ceRNAs. Thus, our study may provide insights into the functional interactions of lncRNA, miRNA and mRNA, and lead to new theories for the pathogenesis and treatment of pulmonary fibrosis.

All-transretinoic acid ameliorates bleomycin-induced lung fibrosis by downregulating the TGF-β1/Smad3 signaling pathway in rats

The transforming growth factor-β1 (TGF-β1)/Smad3 signaling pathway has a central role in pathogenesis of lung fibrosis. In the present study, we investigated if all-trans retinoic acid (ATRA) could attenuate fibrosis in bleomycin (BLM)-induced lung fibrosis in rats through regulating TGF-β1/Smad3 signaling. Beginning on day 14 after BLM administration, the ATRA I and II groups of rats received daily oral administration of ATRA for 14 days. All rats were killed on day 28. Lung tissue sections were prepared and subject to histological assessment, and expression levels of proteins involved in the TGF-β1 signaling cascade and epithelial-mesenchymal transition (EMT) were evaluated by transmission electron microscopy (TEM), quantitative real-time polymerase chain reaction (qRT-PCR), western blot procedure, and immunohistochemical or immunofluorescence staining. BLM significantly increased the alveolar septum infiltrates, inflammatory cell infiltrates, and collagen fibers. These BLM-induced changes were significantly ameliorated by ATRA treatment. In addition, BLM significantly increased levels of lung fibrosis markers α-SMA, hydroxyproline (Hyp), collagen I, Snail, and Twist, whereas significantly decreased E-cadherin expression. ATRA treatment largely reversed BLM-induced changes in these lung fibrosis markers. ATRA also blocked BLM-induced activation of the TGF-β1/Smad3 signaling pathway in lung tissues, including expression of TGF-β1, Smad3, p-Smad3, zinc-finger E-box-binding homeobox 1 and 2 (ZEB1 and ZEB2), and the high-mobility group AT-hook 2 (HMGA2). Our results suggest that ATRA may have potential therapeutic value for lung fibrosis treatment.