Baicalin is anti-inflammatory in cigarette smoke-induced inflammatory models in vivo and in vitro: A possible role for HDAC2 activity.

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease characterized by airway obstruction and progressive lung inflammation, which is insensitive to corticosteroids therapies. In this study, we investigated the mechanism underlying the attenuation of cigarette smoke (CS)-induced respiratory inflammation by baicalin, a flavonoid compound isolated from the root of Scutellaria baicalensis Georgi, in vivo and in vitro. In vivo, mice were exposed to smoke of 15 cigarettes for 1 h/day, 6 days/week for 3 months and dosed with baicalin (25, 50 and 100mg/kg) or dexamethasone (1mg/kg). In vitro, A549 cells were incubated with baicalin (10, 50 and 100 μM) or dexamethasone (10(-12), 10(-10), 10(-8) and 10(-6)M) followed by treatments with cigarette smoke extract (CSE, 2.5 and 5%), or TNF-α (10 ng/ml), or trichostatin A (TSA, 100 ng/ml). We found that baicalin significantly protected pulmonary function and attenuated CS-induced inflammatory response by decreasing inflammatory cells and production of TNF-α, IL-8 and MMP-9. This result was not found in the group treated with dexamethasone. Baicalin also showed efficacy in enhancing histone deacetylase (HDAC)2 activity and protein expression, however, it did not affect HDAC2 mRNA. Further studies revealed that baicalin inhibited HDAC2 phosphorylation, suggesting that it may directly affect the protein structure and effect by modification at post-translational level. Together these results suggest that baicalin has anti-inflammatory effects in cigarette smoke induced inflammatory models in mice and A549 cells, possibly achieved by modulating HDAC2.

Li L ，Bao H ，Wu J ，Duan X ，Liu B ，Sun J ，Gong W ，Lv Y ，Zhang H ，Luo Q ，Wu X ，Dong J ... -  《-》

Baicalin attenuates inflammation by inhibiting NF-kappaB activation in cigarette smoke induced inflammatory models.

Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappaB) is a key player in the inflammatory response. Baicalin is an extract from roots of the plant scutellaria baicalensis. Many studies show that baicalin has anti-inflammatory, anti-bacterial and antiviral activities. Here we investigated the influence of baicalin on COPD inflammation and the mechanism of anti-inflammatory effect in vivo and in vitro. In vivo, COPD rat model was established by cigarette smoke (CS) exposure. Thirty-six Sprague-Dawley (SD) rats were randomly assigned to six experimental groups: control, CS, dexamethasone (DXM), and baicalin (20 mg/kg, 40 mg/kg, 80 mg/kg). The lung pathology was observed and leukocytes in bronchoalveolar lavage fluid (BALF) were counted by Optical microscope. Pulmonary function was measured by using an animal plethysmograph. The production of cytokines was measured by ELISA and the expression levels of NF-kappaB p65 protein were detected by immunohistochemistry. The results in vivo show CS exposure significantly increased the expression of IL-8, IL-6 and TNF-alpha in plasma and BALF and enhanced NF-kappaB p65 expression in the lungs. Baicalin treatment markedly attenuated the inflammatory effects of CS. In vitro, cell model was established by using cigarette smoke extract (CSE) to stimulate type II pneumocytes. Type II pneumocytes were also divided into six groups: control, CSE, pyrrolidine dithiocarbamate (PDTC), and baicalin (5 mumol, 10 mumol, 20 mumol). Cytokines levels were measured by ELISA. Expression of IkappaB and p65 phosphorylation was detected by western blotting. NF-kappaB DNA-binding activity was detected by EMSA. The results show that CSE resulted in increasing IL-8, IL-6 and TNF-alpha expression and activation of NF-kappaB. The proinflammatory effects of CSE were inhibited by treatment of baicalin in a dose-dependent manner. It can be concluded that baicalin has significant anti-inflammatory effects on CS induced COPD rat models and CSE-induced cell models, and the effectiveness increases with increasing baicalin dosage. The anti-inflammatory effect is likely achieved by inhibiting the NF-kappaB pathway.

Lixuan Z ，Jingcheng D ，Wenqin Y ，Jianhua H ，Baojun L ，Xiaotao F ... -  《-》

Baicalin ameliorates cigarette smoke-induced airway inflammation in rats by modulating HDAC2/NF-κB/PAI-1 signalling.

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease distinguished by airway remodelling and progressive inflammation. PAI-1 is an important regulator of fibrosis. Recent studies have shown that PAI-1 seems to be involved in COPD progression. Elevated levels of PAI-1 have been found in the lungs of patients with acute inflammation. PAI-1 has been shown to regulate the levels of proinflammatory cytokines in the lungs, such as tumour necrosis factor (TNF)-α and interleukin (IL)-6, indicating that PAI-1 may play a fundamental role during inflammation. In the present study, we investigated the anti-inflammatory role of baicalin, the main active component of Scutellaria baicalensis, against cigarette smoke (extract) (CS/CSE)-induced airway inflammation in vivo and in vitro. For the in vivo study, SD rats were exposed to CS for 1 h/day, 6 days/week, for 24 weeks and treated with baicalin (40, 80 and 160 mg/kg) or budesonide (0.2 mg/kg). For this study, HBE cells were pretreated with baicalin (10, 20, 40 μM) or dexamethasone (10-7 M) and then exposed to CSE. We found that baicalin treatment could ameliorate CS-induced airway inflammatory infiltration in rats and decrease PAI-1 expression. The ELISA results showed that baicalin significantly inhibited the levels of TNF-α and IL-1β in CS/CSE-exposed rats and cells. Mechanistic studies showed that baicalin enhanced histone deacetylase 2 (HDAC2) protein expression and inhibited the expression of NF-κB and its downstream target PAI-1, and these effects were reversed by the HDAC2 inhibitor CAY-10683. In conclusion, baicalin ameliorated CS-induced airway inflammation in rats, and these effects were partially attributed to the modulation of HDAC2/NF-κB/PAI-1 signalling.

Zhang H ，Liu B ，Jiang S ，Wu JF ，Qi CH ，Mohammadtursun N ，Li Q ，Li L ，Zhang H ，Sun J ，Dong JC ... -  《-》

Protective effects of liquiritin apioside on cigarette smoke-induced lung epithelial cell injury.

Guan Y ，Li FF ，Hong L ，Yan XF ，Tan GL ，He JS ，Dong XW ，Bao MJ ，Xie QM ... -  《-》

Quercetin attenuates airway inflammation and mucus production induced by cigarette smoke in rats.

Mucus hypersecretion is a feature of many chronic airway diseases induced by cigarette smoke (CS), and evidence suggests that the antioxidant and anti-inflammatory flavonoid quercetin may protect against CS-induced respiratory pathology. In this study, the ability of quercetin to protect against CS-induced mucin expression was examined in vivo and in vitro. Quercetin or 0.2% Tween aqueous solution was administered intraperitoneally to rats,which were then exposed to CS for 28 days. Cell counts and pro-inflammatory cytokine levels were measured in bronchoalveolar lavage fluid (BALF). Lung tissue was examined for total glutathione (GSH) and total antioxidant capacity (T-AOC), histopathological lesions, goblet cell hyperplasia, epidermal growth factor receptor (EGFR) phosphorylation and NF-κB pathway activation. To complement these in vitro studies, human airway epithelial NCI-H292 cells were pretreated with quercetin and then exposed to cigarette smoke extract (CSE). Cell lysates were examined for Muc5ac expression, EGFR phosphorylation and NF-κB pathway activation. In vivo, quercetin pretreatment suppressed CS-induced goblet cell hyperplasia, inflammation, oxidative stress, EGFR phosphorylation and NF-κB pathway activation in rat lung. In vitro, quercetin pretreatment attenuated the CSE-induced Muc5ac expression, NF-κB activation and EGFR phosphorylation. Our results suggest that quercetin attenuates CS-induced mucin protein synthesis in rat lung, possibly by inhibiting oxidative stress and inflammation via a mechanism involving NF-κB pathway activation and EGFR phosphorylation. These findings suggest that quercetin has a potential for treating chronic airway diseases.

Yang T ，Luo F ，Shen Y ，An J ，Li X ，Liu X ，Ying B ，Liao Z ，Dong J ，Guo L ，Wang T ，Xu D ，Chen L ，Wen F ... -  《-》