Silymarin attenuates airway inflammation induced by cigarette smoke in mice

Silymarin and Inflammation: Food for Thoughts

Inflammation is a vital defense mechanism, creating hostile conditions for pathogens, preventing the spread of tissue infection and repairing damaged tissues in humans and animals. However, when inflammation resolution is delayed or compromised as a result of its misregulation, the process proceeds from the acute phase to chronic inflammation, leading to the development of various chronic illnesses. It is proven that redox balance disturbances and oxidative stress are among major factors inducing NF-κB and leading to over-inflammation. Therefore, the anti-inflammatory properties of various natural antioxidants have been widely tested in various in vitro and in vivo systems. Accumulating evidence indicates that silymarin (SM) and its main constituent silibinin/silybin (SB) have great potential as an anti-inflammation agent. The main anti-inflammatory mechanism of SM/SB action is attributed to the inhibition of TLR4/NF-κB-mediated signaling pathways and the downregulated expression of pro-inflammatory mediators, including TNF-α, IL-1β, IL-6, IL-12, IL-23, CCL4, CXCL10, etc. Of note, in the same model systems, SM/SB was able to upregulate anti-inflammatory cytokines (IL-4, IL-10, IL-13, TGF-β, etc.) and lipid mediators involved in the resolution of inflammation. The inflammatory properties of SM/SB were clearly demonstrated in model systems based on immune (macrophages and monocytes) and non-immune (epithelial, skin, bone, connective tissue and cancer) cells. At the same time, the anti-inflammatory action of SM/SB was confirmed in a number of in vivo models, including toxicity models, nonalcoholic fatty liver disease, ischemia/reperfusion models, stress-induced injuries, ageing and exercising models, wound healing and many other relevant model systems. It seems likely that the anti-inflammatory activities of SM/SB are key elements on the health-promoting properties of these phytochemicals.

Polyphenols, flavonoids and inflammasomes: the role of cigarette smoke in COPD

COPD is predicted to become the third leading cause of morbidity and mortality worldwide by 2030. Cigarette smoking (active or passive) is one of its chief causes, with about 20% of cigarette smokers developing COPD from cigarette smoke (CS)-induced irreversible damage and sustained inflammation of the airway epithelium. Inflammasome activation leads to the cleavage of pro-interleukin (IL)-1β and pro-IL-18, along with the release of pro-inflammatory cytokines via gasdermin D N-terminal fragment membrane pores, which further triggers acute phase pro-inflammatory responses and concurrent pyroptosis. There is currently intense interest in the role of nucleotide-binding oligomerisation domain-like receptor family, pyrin domain containing protein-3 inflammasomes in chronic inflammatory lung diseases such as COPD and their potential for therapeutic targeting. Phytochemicals including polyphenols and flavonoids have phyto-medicinal benefits in CS-COPD. Here, we review published articles from the last decade regarding the known associations between inflammasome-mediated responses and ameliorations in pre-clinical manifestations of CS-COPD via polyphenol and flavonoid treatment, with a focus on the underlying mechanistic insights. This article will potentially assist the development of drugs for the prevention and therapy of COPD, particularly in cigarette smokers.

This review compiles current investigations into the role of polyphenols/flavonoids in the alleviation of cigarette smoke-induced inflammasome; notably it provides a promising hit for rectifying the treatment of COPD.https://bit.ly/36OcUO9

Potential Natural Small Molecular Compounds for the Treatment of Chronic Obstructive Pulmonary Disease: An Overview

Chronic obstructive pulmonary disease (COPD) is one of the major diseases threatening human life and health. According to the report released by the World Health Organization (WHO) in 2020, COPD has become the third leading cause of death in the world, featuring a sustainable growth of incidence rate as well as population age. The purpose of this review focuses on the advancement of bioactive natural compounds, such as baicalin, quercetin, resveratrol, and curcumin, which demonstrate promising therapeutic/interventional effects on CODP in vitro and in vivo. Information emphasizing on COPD was systematically collected from several authoritative internet databases including Web of Science, PubMed, Elsevier, Wiley Online Library, and Europe PMC, with a combination of keywords containing “COPD” and “natural small molecular compounds”. The new evidence indicated that these valuable molecules featured unique functions in the treatment of COPD through various biological processes such as anti-inflammatory, anti-oxidant, anti-apoptosis, and anti-airway fibrosis. Moreover, we found that the promising effects of these natural compounds on COPD were mainly achieved through JAK3/STAT3/NF-κB and MAPK inflammatory signaling pathways, Nrf2 oxidative stress signaling pathway, and TGF-β1/Smad 2/3 fibrosis signaling pathway, which referenced to multiple targets like TNF-α, IL-6, IL-8, TIMP-1, MMP, AKT, JAK3, IKK, PI3K, HO-1, MAPK, P38, ERK, etc. Current challenges and future directions in this promising field are also discussed at the end of this review. For the convenience of the readers, this review is divided into ten parts according to the structures of potential natural small molecular compounds. We hope that this review brings a quick look and provides some inspiration for the research of COPD.

Mitochondrial-Targeting Antioxidant SS-31 Suppresses Airway Inflammation and Oxidative Stress Induced by Cigarette Smoke

This study investigated whether the mitochondrial-targeted peptide SS-31 can protect against cigarette smoke- (CS-) induced airway inflammation and oxidative stress in vitro and in vivo. Mice were exposed to CS for 4 weeks to establish a CS-induced airway inflammation model, and those in the experimental group were pretreated with SS-31 1 h before CS exposure. Pathologic changes and oxidative stress in lung tissue, inflammatory cell counts, and proinflammatory cytokine levels in bronchoalveolar lavage fluid (BALF) were examined. The mechanistic basis for the effects of SS-31 on CS extract- (CSE-) induced airway inflammation and oxidative stress was investigated using BEAS-2B bronchial epithelial cells and by RNA sequencing and western blot analysis of lung tissues. SS-31 attenuated CS-induced inflammatory injury of the airway and reduced total cell, neutrophil, and macrophage counts and tumor necrosis factor- (TNF-) α, interleukin- (IL-) 6, and matrix metalloproteinase (MMP) 9 levels in BALF. SS-31 also attenuated CS-induced oxidative stress by decreasing malondialdehyde (MDA) and myeloperoxidase (MPO) activities and increasing that of superoxide dismutase (SOD). It also reversed CS-induced changes in the expression of mitochondrial fission protein (MFF) and optic atrophy (OPA) 1 and reduced the amount of cytochrome c released into the cytosol. Pretreatment with SS-31 normalized TNF-α, IL-6, and MMP9 expression, MDA and SOD activities, and ROS generation in CSE-treated BEAS-2B cells and reversed the changes in MFF and OPA1 expression. RNA sequencing and western blot analysis showed that SS-31 inhibited CS-induced activation of the mitogen-activated protein kinase (MAPK) signaling pathway in vitro and in vivo. Thus, SS-31 alleviates CS-induced airway inflammation and oxidative stress via modulation of mitochondrial function and regulation of MAPK signaling and thus has therapeutic potential for the treatment of airway disorders caused by smoking.

Advances in Pharmacological Actions and Mechanisms of Flavonoids from Traditional Chinese Medicine in Treating Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common respiratory disease with high morbidity and mortality. The conventional therapies remain palliative and have various undesired effects. Flavonoids from traditional Chinese medicine (TCM) have been proved to exert protective effects on COPD. This review aims to illuminate the poly-pharmacological properties of flavonoids in treating COPD based on laboratory evidences and clinical data and points out possible molecular mechanisms. Animal/laboratory studies and randomised clinical trials about administration of flavonoids from TCM for treating COPD from January 2010 to October 2020 were identified and collected, with the following terms: chronic obstructive pulmonary disease or chronic respiratory disease or inflammatory lung disease, and flavonoid or nature product or traditional Chinese medicine. Pharmacokinetic studies and external application treatment were excluded. A total of 15 flavonoid compounds were listed. Flavonoids could inhibit inflammation, oxidative stress, and cellular senescence, restore corticosteroid sensitivity, improve pulmonary histology, and boost pulmonary function through regulating multiple targets and signaling pathways, which manifest that flavonoids are a group of promising natural products for COPD. Nevertheless, most studies remain in the research phase of animal testing, and further clinical applications should be carried out.

Schisantherin A Inhibits Pulmonary Fibrosis via Regulating ERK Signaling Pathway

There is no effective method for treating pulmonary fibrosis (PF) until now. This study investigated the anti-fibrotic effect of schisantherin A (SCA) extracted from Schisandra chinensis and its potential molecular mechanism in PF. A bleomycin-induced PF mouse model in vivo and transforming growth factor (TGF)-β1-induced A549 epithelial-mesenchymal transition (EMT) cell model in vitro were used for assessing the anti-fibrotic effect of SCA. Histopathological examination was conducted after hematoxylin and eosin and Masson staining. The level of TGF-β1 was tested by ELISA. The expression levels of α-smooth muscle actin, E-cadherin, and inflammatory cytokines (COX2, IL-1β, IL-6, and TNF-α) were determined by quantitative reverse transcription polymerase chain reaction and Western blot. The expression of extracellular signal-regulated kinase (ERK) was tested in lung tissues and cells by Western blot. The in vivo experiments revealed that SCA treatment markedly improved body weight and pulmonary index and reformed the destruction of the lung tissue structure. We observed that SCA inhibited the process of TGF-β1-induced EMT in the in vitro experiments. Inflammatory cytokines were reduced greatly in lung tissues and cells by SCA. Our study also indicated that SCA decreased phosphorylated ERK. It was concluded that SCA can attenuate PF by regulating the ERK signaling pathway, which suggests that SCA may be used as a potential therapeutic drug for PF.

Serotonin receptors 5-HTR2A and 5-HTR2B are involved in cigarette smoke-induced airway inflammation, mucus hypersecretion and airway remodeling in mice

BACKGROUND

Cigarette smoke plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Recently, elevated serotonin (5-HT) levels were found in the plasma of COPD patients. The role of 5-HT and its receptors in airway inflammation and remodeling induced by cigarette smoke is unclear.

METHODS

BALB/c mice received the 5-HTR2A inhibitor ketanserin, the 5-HTR2B inhibitor RS-127445 or the natural 5-HTR2A/2B inhibitor quercetin intraperitoneally, then were exposed to cigarette smoke for 6 or 12 weeks. Control mice received placebo and were exposed to room air or cigarette smoke. Mice were sacrificed and bronchial alveolar lavage fluid (BALF) and lung tissue samples were collected.

RESULTS

Immunohistochemistry and western blot confirmed an increase in both 5-HTR2A and 5-HTR2B expression in mouse lungs after exposure to cigarette smoke for 6 and 12 weeks. Cigarette smoke induced accumulation of macrophages and neutrophils and increased levels of inflammatory cytokines, including IL-1β and TNF-ɑ, in BALF and lung tissue; these effects were inhibited by ketanserin, RS-127445 and quercetin. Pretreatment with 5-HT receptor antagonists suppressed the goblet cell hyperplasia induced by 6- or 12-week exposure to cigarette smoke, based on Alcian blue-periodic acid Schiff staining. After 12 weeks of cigarette smoke exposure, Masson's staining showed fibrosis surrounding the mouse airways, and inhibitor pretreatment significantly attenuated the thickening and collagen deposition around the small airways.

CONCLUSIONS

Our results suggest that cigarette smoke-induced airway inflammation and small airway remodeling are partially mediated by 5-HTR2A and 5-HTR2B, which could be a new therapeutic target for airway remodeling in COPD.

Effects of silymarin on p65 NF-κB, p38 MAPK and CYP450 in LPS-induced hoof dermal inflammatory cells of dairy cows

Background

Laminitis is considered as one of the most important causes of hoof lameness in dairy cows, which can lead to enormous economic losses. However, the etiology and pathogenesis of laminitis have not been clarified yet. Besides, it is of great significant to find alternative herbs for the prevention and treatment of dairy hooves to avoid the antibiotic abuse. In this study, the primary hoof dermal cells of dairy cows were isolated, the inflammatory model was induced by LPS, and treated with silymarin to find whether silymarin has protective effect on the inflammatory dermal cells. The viability of dermal cells, the levels of IL-1β and TNF-α, the degree of p65 NF-κB and p38 MAPK phosphorylation, the expressions of CYP3A4 and CYP1A1 were measured.

Results

Hoof dermal cells of dairy cows were successfully isolated and cultured by tissue adherent culture method. Certain concentrations of LPS can increase the levels of IL-1β and TNF-α, promote the phosphorylation of p65 NF-κB and p38 MAPK, and inhibit the mRNA expressions of CYP3A4 and CYP1A1. The optimal concentration for LPS to establish a hoof dermal cells inflammatory model was 10 μg/mL. Certain concentrations of silymarin can markedly decrease the secretions of IL-1β and TNF-α, inhibit the phosphorylation of p65 NF-κB and p38 MAPK, and promote the mRNA expressions of CYP3A4 and CYP1A1 in LPS-induced dermal inflammatory model.

Conclusions

LPS can be used for inducing the hoof dermal cells inflammatory model of dairy cows. Silymarin has protective effects on the LPS-induced inflammatory model.

Annexin A1 is elevated in patients with COPD and affects lung fibroblast function

Purpose

Fibrosis in peripheral airways is responsible for airflow limitation in chronic obstructive pulmonary disease (COPD). Annexin A1 modulates several key biological events during inflammation. However, little is known about its role in airway fibrosis in COPD. We investigated whether levels of Annexin A1 were upregulated in patients with COPD, and whether it promoted airway fibrosis.

Methods

We quantified serum Annexin A1 levels in never-smokers (n=12), smokers without COPD (n=11), and smokers with COPD (n=22). Correlations between Annexin A1 expression and clinical indicators (eg, lung function) were assessed. In vitro, human bronchial epithelial (HBE) cells were exposed to cigarette smoke extract (CSE) and Annexin A1 expression was assessed. Primary human lung fibroblasts were isolated from patients with COPD and effects of Annexin A1 on fibrotic deposition of lung fibroblasts were evaluated.

Results

Serum Annexin A1 was significantly higher in patients with Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines stage III or IV than in those with GOLD stages I or II (12.8±0.8 ng/mL versus 9.8±0.7 ng/mL; p=0.016). Annexin A1 expression was negatively associated with airflow obstruction (forced expiratory volume in one second % predicted; r=−0.72, p<0.001). In vitro, Annexin A1 was significantly increased in CSE-exposed HBE cells in a time- and concentration-dependent manner. Annexin A1 promoted lung fibroblasts proliferation, migration, differentiation, and collagen deposition via the ERK1/2 and p38 mitogen-activated protein kinase pathways.

Conclusion

Annexin A1 expression is upregulated in patients with COPD and affects lung fibroblast function. However, more studies are needed to clarify the role of Annexin A1 in airway fibrosis of COPD.

Phloretin attenuates mucus hypersecretion and airway inflammation induced by cigarette smoke

BACKGROUNDS

Cigarette smoke (CS)-induced airway mucus hypersecretion and inflammation are the prominent features of chronic obstructive pulmonary disease (COPD). As an anti-inflammatory flavonoid, phloretin was found to be involved in various inflammatory disorders such as sepsis. In this study, the effects of phloretin on CS-induced airway mucin secretion and inflammation were investigated in vivo and in vitro.

METHODS

Phloretin dissolved in 1% DMSO was daily injected intraperitoneally to mice, which were then exposed to CS for four weeks. Mouse lung histologic changes were evaluated, the expression of mucin 5ac (MUC5AC) was measured, bronchoalveolar lavage fluid (BALF) total cells, neutrophils, and macrophages were counted. BALF and lung levels of tumor necrosis factor-alpha and interleukin-1 beta (IL-1β) were quantified. Moreover, the effects of phloretin on cigarette smoke extract (CSE)-induced expression of MUC5AC and IL-1β were investigated in NCI-H292 cells. Then, to explore the potential mechanisms, the signaling molecules including epidermal growth factor receptor (EGFR), extracellular signal-regulated kinase (ERK) and P38 were evaluated.

RESULTS

Phloretin pretreatment dramatically suppressed the mucins secretion, inflammatory cell infiltration and inflammatory cytokine release in mouse lungs induced by CS, and it also suppressed CSE-induced expression of MUC5AC and IL-1β in NCI-H292 bronchial epithelial cells. Furthermore, western blot showed that phloretin attenuated the activation of EGFR, ERK and P38 both in vivo and in vitro.

CONCLUSIONS

This study highlights the protective effect of phloretin on CS-related airway mucus hypersecretion and inflammation, where EGFR, ERK and P38 might be involved. These findings suggest that phloretin could be a potential therapeutic drug for COPD.

Protective effects of neem (Azadirachta indica A. Juss.) leaf extract against cigarette smoke- and lipopolysaccharide-induced pulmonary inflammation

Neem (Azadirachta indica A. Juss.) leaf has been reported to exert anti-inflammatory, antibacterial and antioxidant effects. The purpose of this study was to investigate the protective effects of neem leaf extract (NLE) against cigarette smoke (CS)- and lipopolysaccharide (LPS)-induced pulmonary inflammation. Treatment with NLE significantly attenuated the infiltration of inflammatory cells, such as neutrophils and macrophages in bronchoalveolar lavage fluid (BALF). NLE also reduced the production of reactive oxygen species and the activity of neutrophil elastase in BALF. Moreover, NLE attenuated the release of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 in BALF. NLE inhibited the recruitment of inflammatory cells and the expression of monocyte chemoattractant protein-1 (MCP-1) in the lungs of mice with CS- and LPS-induced pulmonary inflammation. NLE also decreased the expression of inducible nitric oxide synthase (iNOS) in the lungs of the mice CS- and LPS-induced pulmonary inflammation. Furthermore, treatment with NLE significantly attenuated the activation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) in the lungs mice exposed to CS and LPS. NLE also inhibited the phosphorylation of nuclear factor (NF)-κB and inhibitor of NF-κB (IκB) in the lungs of mice expose to CS and LPS. These findings thus suggest that NLE has potential for use in the treatment of chronic obstructive pulmonary disease.

Physalis peruviana L. inhibits airway inflammation induced by cigarette smoke and lipopolysaccharide through inhibition of extracellular signal-regulated kinase and induction of heme oxygenase-1

Physalis peruviana L. (PP) is a medicinal herb that has been confirmed to have several biological activities, including anticancer, antioxidant and anti-inflammatory properties. The aim of the present study was to evaluate the protective effect of PP on cigarette smoke (CS)- and lipopolysaccharide (LPS)-induced pulmonary inflammation. Treatment with PP significantly reduced the influx of inflammatory cells in the bronchoalveolar lavage fluid (BALF) and lung of mice with CS- and LPS-induced pulmonary inflammation. PP also decreased the levels of reactive oxygen species (ROS) and pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in the BALF. PP effectively attenuated the expression of monocyte chemoattractant protein-1 (MCP-1) and the activation of extracellular signal-regulated kinase (ERK) in the lung. In addition, nuclear factor erythroid 2-related factor 2 (Nrf2) activation and heme oxygenase-1 (HO-1) expression were increased by PP treatment. In an in vitro experiment, PP reduced the mRNA expression of TNF-α and MCP-1, and the activation of ERK in CS extract-stimulated A549 epithelial cells. Furthermore, PP increased the activation of Nrf2 and the expression of HO-1 in A549 cells. These findings suggest that PP has a therapeutic potential for the treatment of pulmonary inflammatory diseases, such as chronic obstructive pulmonary disease.

A standardized bark extract of Pinus pinaster Aiton (Pycnogenol®) attenuated chronic obstructive pulmonary disease via Erk-sp1 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

A standardized bark extract of Pinus pinaster Aiton (Pycnogenol^®; PYC) used as an herbal medicine to treat various diseases in Europe and North America.

AIM OF THE STUDY

This study evaluates the ability of PYC to inhibit chronic obstructive pulmonary disease (COPD) in the cigarette smoke extract (CSE)-stimulated human airway epithelial cell line NCI-H292 and in a cigarette smoke (CS) and lipopolysaccharide (LPS)-induced mouse model.

METHODS

To induce COPD, the mice intranasally received LPS on day 4 and were exposed to CS for 1h per day (total eight cigarettes per day) from days 1-7. The mice were administered PYC at a dose of 15mg/kg and 30mg/kg 1h before CS exposure.

RESULTS

In the CSE-stimulated NCI-H292 cells, PYC significantly inhibited Erk phosphorylation, sp1 expression, MUC5AC, and pro-inflammatory cytokines in a concentration-dependent manner, as evidenced by a reduction in their mRNA levels. Co-treatment with PYC and Erk inhibitors markedly reduced the levels inflammatory mediators compared to only PYC-treatment. In the COPD mice model, PYC decreased the inflammatory cell count and the levels of pro-inflammatory cytokines in the broncho-alveolar lavage fluid compared with COPD mice. PYC attenuated the recruitment of inflammatory cells in the airways and decreased the expression levels of Erk phosphorylation and sp1. PYC also inhibited the expression of myeloperoxidase and matrix metalloproteinases-9 in lung tissue.

CONCLUSION

Our results indicate that PYC inhibited the reduction in the inflammatory response in CSE-stimulated NCI-H292 cells and the COPD mouse model via the Erk-sp1 pathway. Therefore, we suggest that PYC has the potential to treat COPD.

Silymarin attenuates cigarette smoke extract-induced inflammation via simultaneous inhibition of autophagy and ERK/p38 MAPK pathway in human bronchial epithelial cells

Cigarette smoke (CS) is a major risk of chronic obstructive pulmonary disease (COPD), contributing to airway inflammation. Our previous study revealed that silymarin had an anti-inflammatory effect in CS-exposed mice. In this study, we attempt to further elucidate the molecular mechanisms of silymarin in CS extract (CSE)-induced inflammation using human bronchial epithelial cells. Silymarin significantly suppressed autophagy activation and the activity of ERK/p38 mitogen-activated protein kinase (MAPK) pathway in Beas-2B cells. We also observed that inhibiting the activity of ERK with specific inhibitor U0126 led to reduced autophagic level, while knockdown of autophagic gene Beclin-1 and Atg5 decreased the levels of ERK and p38 phosphorylation. Moreover, silymarin attenuated CSE-induced upregulation of inflammatory cytokines TNF-α, IL-6 and IL-8 which could also be dampened by ERK/p38 MAPK inhibitors and siRNAs for Beclin-1 and Atg5. Finally, we validated decreased levels of both autophagy and inflammatory cytokines (TNF-α and KC) in CS-exposed mice after silymarin treatment. The present research has demonstrated that CSE-induced autophagy in bronchial epithelia, in synergism with ERK MAPK pathway, may initiate and exaggerate airway inflammation. Silymarin could attenuate inflammatory responses through intervening in the crosstalk between autophagy and ERK MAPK pathway, and might be an ideal agent treating inflammatory pulmonary diseases.

Effects of benzo[a]pyrene as an environmental pollutant and two natural antioxidants on biomarkers of reproductive dysfunction in male rats

Benzo[a]pyrene (B[a]P) is an environmental toxicant and endocrine disruptor. Therefore, the aim of the present study was to investigate the toxicity of B[a]P in testis of rats and also to study the role of silymarin and thymoquinone (TQ) as natural antioxidants in the alleviation of such toxicity. Data of the present study showed that levels of testosterone, estrogen and progesterone were significantly decreased after treatment of rats with B[a]P. In addition, B[a]P caused downregulation of the expressions of steroidogenic enzymes including CYP17A1 and CP19A1, and decreased the activity of 17-β hydroxysteroid dehydrogenase (17β-HSD). Moreover, B[a]P decreased the activities of antioxidant enzymes including catalase (CAT), glutathione peroxidase (GPX) and superoxide dismutase (SOD), and significantly increased free radicals levels in testis of male rats. However, pretreatment of rats with silymarin prior to administration of B[a]P was found to restore the level of free radicals, antioxidant status, and activities of steroidogenic enzymes to their normal levels in testicular tissues. Moreover, histopathological finding showed that silymarin recovered the abnormalities occurred in tubules caused by B[a] P in testis of rats. On the other hand, TQ showed pro-oxidant effects and did not ameliorate the toxic effects of B[a] P on the testicular tissue since it decreased antioxidant enzymes activities and inhibited the protein expression of CYP11A1 and CYP21A2 compared to control rats. Moreover, TQ decreased the levels of testosterone, estrogen, and progesterone either in the presence or absence of B[a]P. It is concluded that B[a]P decreased testosterone levels, inhibited antioxidant enzymes activities, caused downregulation of CYP isozymes involved in steroidogenesis, and increased free radical levels in testis. Moreover, silymarin was more effective than TQ in restoring organism health and alleviating the deleterious effects caused by B[a]P in the testis of rats. Due to its negative impact, it is highly recommended to limit the use of TQ as a dietary supplement since millions of people in the Middle East are using it to improve their health.

Asiatic acid inhibits pulmonary inflammation induced by cigarette smoke

Asiatic acid (AA) is one of the major components of Titrated extract of Centella asiatica (TECA), which has been reported to possess antioxidant and anti-inflammatory activities. The purpose of this study was to investigate the protective effect of AA on pulmonary inflammation induced by cigarette smoke (CS). AA significantly attenuated the infiltration of inflammatory cells in bronchoalveolar lavage fluid (BALF) of CS exposure mice. AA also decreased ROS production and NE activity, and inhibited the release of proinflammatory cytokines in BALF. AA reduced the recruitment of inflammatory cells and MCP-1 expression in lung tissue of CS exposure mice. AA also attenuated mucus overproduction, and decreased the activation of MAPKs and NF-kB in lung tissue. Furthermore, AA increased HO-1 expression and inhibited the reduced expression of SOD3 in lung tissue. These findings indicate that AA effectively inhibits pulmonary inflammatory response, which is an important process in the development of chronic obstructive pulmonary disease (COPD) via suppression of inflammatory mediators and induction of HO-1. Therefore, we suggest that AA has the potential to treat inflammatory disease such as COPD.

Protective role of silymarin in a mouse model of renal Ischemia-Reperfusion injury

BACKGROUND

We investigated the mechanism of action of silymarin in a mouse model of renal ischemia-reperfusion injury (I/R) to ascertain its role in the treatment of I/R injury.

METHODS

Twenty-four C57BL/6 male mice were divided randomly into three groups: control (sham); ischemia-reperfusion (I/R); silymarin + ischemia-reperfusion (silymarin + I/R). In sham mice, an abdominal incision was made, followed by dissection of the bilateral renal pedicle, with no further cross-clamping of arteries. Silymarin + I/R mice were administered 100 mg/kg silymarin daily for 7 consecutive days before surgery, whereas I/R mice were administered (i.g.) 0.9 % saline + 0.1 % (v/v) ethanol daily for 7 consecutive days before surgery. Silymarin + I/R and I/R mice were subjected to renal ischemia to induce acute kidney injury after 45-min clamping of bilateral renal arteries. Serum levels of creatinine and blood urea nitrogen levels were measured. Periodic acid-Schiff (PAS) staining was undertaken to detect damaged renal tissue. Myeloperoxidase (MPO) activity and immunofluorescent detection of CD68 expression was undertaken for each group. Levels of inflammatory cytokines secreted by renal tissue were monitored by ELISA. Apoptosis was detected by TUNEL staining. Expression of cleaved-caspase-3, Bcl-2 and Bax was detected by western blotting.

RESULTS

Serum creatinine and blood urea nitrogen levels were elevated in silymarin + I/R and I/R groups compared with sham mice (p < 0.05), whereas those in the I/R group were significantly higher than in the silymarin + I/R group (p < 0.05). Number of damaged renal tubule cells and apoptotic cells in sham and silymarin + I/R groups was significantly lower than in I/R mice. MPO activity and secretion of inflammatory cytokines in silymarin + I/R and I/R groups was reduced (p < 0.05), and CD68 expression in silymarin + I/R mice was lower than in I/R mice (p < 0.05). Expression of cleaved-caspase-3 and Bax in the I/R group was significantly higher than in sham mice, whereas Bcl-2 expression was lower than in silymarin + I/R mice (p < 0.05).

CONCLUSIONS

Silymarin can inhibit renal I/R injury by inhibiting release of inflammatory factors and regulating apoptosis.

Silymarin attenuates paraquat-induced lung injury via Nrf2-mediated pathway in vivo and in vitro

The present study aims to investigate the impacts and mechanisms of silymarin on paraquat (PQ)-induced lung injury in vivo and in vitro. In in vivo experiments, a total of 32 male Sprague-Dawley (SD) rats were randomly divided into four groups. The rats were killed on day 3. Histopathological changes in lung tissue were examined using HE and Masson's trichrome staining. Biomarkers of neutrophil activation, pulmonary oedema, pulmonary fibrosis, lung permeability and oxidative stress were detected. Several proinflammatory mediators and antioxidant related proteins were measured. In in vitro experiments, A549 cells were transfected with Nrf2 special siRNA to investigate the roles of Nrf2. The results show that silymarin administration abated PQ-induced lung histopathologic changes, decreased inflammatory cell infiltration and lung wet weight/dry weight (W/D) ratio, suppressed myeloperoxidase (MPO) activity and nitric oxide (NO)/inducible nitric oxide synthases (iNOS) expression, downregulated hydroxyproline (HYP) levels, reduced total protein concentration and proinflammatory mediator release, and improved oxidative stress (malondialdehyde, MDA; superoxide dismutase, SOD; catalase, CAT; and glutathione peroxidase, GSH-Px) in lung tissue and serum. Meanwhile, treatment with silymarin upregulated the levels of nuclear factor-erythroid-2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase-1(NQO1). However, the addition of Nrf2 siRNA reduced the expression of Nrf2-mediated antioxidant protein HO-1 and thus reversed the protective effects of silymarin against oxidative stress and inflammatory response. These results suggest that silymarin may exert protective effects against PQ-induced lung injury. Its mechanisms were associated with the Nrf2-mediated pathway. Therefore, silymarin may be a potential therapeutic drug for lung injury.