Baicalein attenuates bleomycin-induced pulmonary fibrosis in rats through inhibition of miR-21

Baicalein attenuates monocrotaline-induced pulmonary arterial hypertension by inhibiting vascular remodeling in rats

BACKGROUND

Pulmonary arterial hypertension (PAH) is a devastating cardiopulmonary disorder characterized by elevated pulmonary arterial pressure (PAP) and right ventricular hypertrophy (RVH) driven by progressive vascular remodeling. Reversing adverse vascular remodeling is an important concept in the treatment of PAH. Endothelial injury, inflammation, and oxidative stress are three main contributors to pulmonary vascular remodeling. Baicalein is a natural flavonoid that has been shown to possess anti-proliferative, anti-inflammatory, anti-oxidative, and cardioprotective properties. We hypothesized that baicalein may prevent the progression of PAH and preserve the right heart function by inhibiting pulmonary arterial remodeling.

METHODS

Male Sprague-Dawley rats were distributed randomly into 4 groups: control, monocrotaline (MCT)-exposed, and MCT-exposed plus baicalein treated rats (50 and 100 mg/kg/day for 2 weeks). Hemodynamic changes, RVH, and lung morphological features were examined on day 28. Apoptosis was determined by TUNEL staining, and the mRNA levels of tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), and IL-6 were detected by qRT-PCR. The changes in oxidative indicators, including malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were measured using corresponding commercial kits. The levels of Bax, Bcl-2, and cleaved caspase-3, and the activation of mitogen-activated protein kinase (MAPK) and NF-κB were assessed by western blotting.

RESULTS

MCT induced an increase in hemodynamic parameters and RVH, which were attenuated by baicalein treatment. Baicalein also blocked MCT-induced pulmonary arterial remodeling. The levels of apoptotic (Bax/Bcl-2 ratio and cleaved caspase-3) and inflammatory (IL-6, TNF-α, and IL-1β) biomarkers in lung tissue were lower in baicalein-treated groups. Baicalein also decreased MDA level, and increased SOD and GSH-Px activity in rat pulmonary tissue. Furthermore, baicalein inhibited MCT-induced activation of the MAPK and NF-κB pathways.

CONCLUSION

Baicalein ameliorates MCT-induced PAH by inhibiting pulmonary arterial remodeling at least partially via the MAPK and NF-κB pathways in rats.

XIST/miR-139 axis regulates bleomycin (BLM)-induced extracellular matrix (ECM) and pulmonary fibrosis through β-catenin

Pulmonary fibrosis (PF), characterized by the destruction of lung tissue architecture and the abnormal deposition of extracellular matrix (ECM) proteins, currently has no satisfactory treatment. In the present study, we investigated the hypothesis that XIST play a promotive role in bleomycin (BLM)-induced ECM and pulmonary fibrosis; XIST exerts its effect through miR-139 regulation. XIST expression was upregulated in lung tissues derived from BLM-induced mouse model of PF, and was positively correlated with β-catenin and ECM protein levels, respectively. LV-sh-XIST-induced XIST knockdown led to decreased PF, reduced β-catenin and ECM protein levels in lung tissues. XIST knockdown suppressed the proliferation of IMR-90 (human fibroblast) and murine lung fibroblasts (MLFCs) and ECM protein expression. Moreover, miR-139 could directly bind to XIST and the 3’UTR of β-catenin; XIST competed with β-catenin for miR-139 binding both in IMR-90 and MLFCs. In MLFCs, miR-139 inversely regulated XIST, and could partially reverse the effect of XIST on β-catenin and ECM proteins. In lung tissues of PF mice, miR-139 expression was downregulated, whereas β-catenin expression was upregulated. In conclusion, XIST exerts positive effects on BLM-induced PF through inhibiting miR-139 to promote human/mouse fibroblast proliferation and ECM proteins.

Baicalein Attenuates Lung Injury Induced by Myocardial Ischemia and Reperfusion

Baicalein is an active component of Scutellaria baicalensis Georgi, which has traditionally been used to treat cardiovascular diseases in China. In this study, we investigated if treatment with baicalein can attenuate the lung injury induced by myocardial ischemia and reperfusion (I/R). Myocardial I/R, induced by a 40-min occlusion of the left anterior descending coronary artery and a 3-h reperfusion, significantly increased histological damage and the wet-to-dry weight ratio of lungs in rats. The terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive nuclei and caspase-3 activation was significantly increased in the lungs. Serum and bronchoalveolar lavage fluid levels of tumor necrosis factor-[Formula: see text] (TNF-[Formula: see text]), interleukin-1[Formula: see text] (IL-1[Formula: see text]), and interleukin-6 (IL-6) were significantly elevated, as were TNF-[Formula: see text] levels in the lung. Intravenous administration with baicalein at doses of 3, 10, and 30[Formula: see text]mg/kg for ten minutes before myocardial I/R significantly reduced histological damage, the wet-to-dry weight ratio, and apoptosis in the lung. Baicalein also significantly inhibited the increase in levels of TNF-[Formula: see text], IL-1[Formula: see text], and IL-6. Moreover, baicalein increased Bcl-2 and decreased p53, Bax, and cytochrome [Formula: see text] in lungs. Phosphorylation of the prosurvival kinases, including Akt and extracellular signal-regulated kinases 1 and 2 (ERK1/2), was increased, while the phosphorylation of the pro-apoptotic mitogen-activated protein kinases, including p38 and c-Jun N-terminal kinase (JNK), was decreased. In conclusion, treatment with baicalein attenuates the lung injury induced by myocardial I/R. The mechanisms might be related to the limiting of apoptosis, possibly via the inhibition of both the extrinsic and intrinsic pathways of apoptosis, including the inhibition of TNF-[Formula: see text] production and modulation of pro- and anti-apoptotic signaling elements.

Therapeutic potentials of baicalin and its aglycone, baicalein against inflammatory disorders

The flavonoids, baicalin (5,6-dihydroxy-2-phenyl-4H-1-benzopyran-4-one-7-O-d-β-glucuronic acid) 1 and its aglycone, baicalein 2 are found in edible medicinal plants, Scutellaria baicalensis Georgi and Oroxylum indicum (L.) Kurz in abundant quantities. The antioxidant and anti-inflammatory effects of these flavonoids have been demonstrated in various disease models, including diabetes, cardiovascular diseases, inflammatory bowel diseases, gout and rheumatoid arthritis, asthma, neurodegenerative-, liver- and kidney diseases, encephalomyelitis, and carcinogenesis. These flavonoids have almost no toxicity to human normal epithelial, peripheral and myeloid cells. Their antioxidant and anti-inflammatory activities are largely due to their abilities to scavenge the reactive oxygen species (ROS) and improvement of antioxidant status by attenuating the activity of NF-κB and suppressing the expression of several inflammatory cytokines and chemokines including monocyte chemotactic protein-1 (MCP-1), nitric oxide synthase, cyclooxygenases, lipoxygenases, cellular adhesion molecules, tumor necrosis factor and interleukins. In this review, we summarize the antioxidant and anti-inflammatory effects of baicalin and baicalein with molecular mechanisms for their chemopreventive and chemotherapeutic applications in the treatment of inflammatory-related diseases.

Traditional Chinese medicine for pulmonary fibrosis therapy: Progress and future prospects

ETHNOPHARMACOLOGICAL RELEVANCE

Pulmonary fibrosis (PF) is a chronic, debilitating and often lethal lung disorder. Despite the molecular mechanisms of PF are gradually clear with numerous researchers' efforts, few effective drugs have been developed to reverse human PF or even halt the chronic progression to respiratory failure. Traditional Chinese medicine (TCM), the main component of the medical practice used for more than 5000 years especially in China, often exerts wider action spectrum than previously attempted options in treating human diseases. Recent data have shown the anti-fibrotic benefits of the active ingredients from TCM in this field, which may represent an attractive source of the drug discovery against PF.

AIM OF THE REVIEW

This review summarizes the pre-clinical and clinical evidence on the benefits of TCM and their active ingredients, and provides a comprehensive information and reliable basis for the exploration of new treatment strategies of botanical drugs in the therapy of PF.

METHODS

The literature information was obtained from the scientific databases on ethnobotany and ethno medicines (up to Aug 2016), mainly from the Pubmed, Web of Science and CNKI databases, and was to identify the experimental studies on the anti-fibrotic role of the active agents from TCM and the involved mechanisms. The search keywords for such work included: "lung fibrosis" or "pulmonary fibrosis", and "traditional Chinese medicine", "extract" or "herb".

RESULTS

A number of studies have shown that the active agents of single herbs and TCM formulas, particularly the flavonoids, glycosides and alkaloids, exhibit potential benefits against PF, the mechanisms of which appear to involve the regulation of inflammation, oxidant stress, and pro-fibrotic signaling pathways, etc. Besides, the processing methods for discovering TCM in treating PF were prospectively discussed.

CONCLUSION

These research work have shown the therapeutic benefits of TCM in the treatment of PF. However, more continued researches should be undertaken to clarify the unconfirmed chemical composition and regulatory mechanisms, conduct standard clinical trials, and evaluate the possible side effects. The insights provided in present review will be needed for further exploration of botanical drugs in the development of PF therapy.

miR-27b inhibits fibroblast activation via targeting TGFβ signaling pathway

Background

MicroRNAs are a group of small RNAs that regulate gene expression at the posttranscriptional level. They regulate almost every aspect of cellular processes. In this study, we investigated whether miR-27b regulates pulmonary fibroblast activation.

Results

We found that miR-27b was down-regulated in fibrotic lungs and fibroblasts from an experimental mouse model of pulmonary fibrosis. The overexpression of miR-27b with a lentiviral vector inhibited TGFβ1-stimulated mRNA expression of collagens (COL1A1, COL3A1, and COL4A1) and alpha-smooth muscle actin, and protein expression of Col3A1 and alpha-smooth muscle actin in LL29 human pulmonary fibroblasts. miR-27b also reduced contractile activity of LL29. TGFβ receptor 1 and SMAD2 were identified as the targets of miR-27b by 3’-untranslated region luciferase reporter and western blotting assays.

Conclusions

Our results suggest that miR-27b is an anti-fibrotic microRNA that inhibits fibroblast activation by targeting TGFβ receptor 1 and SMAD2. This discovery may provide new targets for therapeutic interventions of idiopathic pulmonary fibrosis.

Effect of the Lipoxygenase Inhibitor Baicalein on Muscles in Ovariectomized Rats

Sarcopenia, a loss of muscle mass accompanying osteoporosis, leads to falls and fall-related injuries. Baicalein, as a phytochemical agent, has an antioxidative and anti-inflammatory effect in muscle. In this study, sixty-one female Sprague Dawley rats were divided into five groups: four groups were ovariectomized (OVX) and one control group was nonovariectomized (NON-OVX). Eight weeks after ovariectomy, three disparate concentrations (1 mg/kg body weight (BW), 10 mg/kg BW, and 100 mg/kg BW) of baicalein were applied subcutaneously daily in three OVX groups. Mm. soleus, gastrocnemius, and longissimus were extracted; their diameter, area, relation to body, and muscle weights as well as number of capillaries per fibre were recorded. In Mm. soleus and gastrocnemius, the baicalein effect (increasing number of capillaries per fibre) was proportional to the dose applied. The fibre diameters and area under baicalein treatment were significantly greater compared to OVX and NON-OVX groups. In M. longissimus, we observed a shift to type IIa fibres. Serum creatine kinase levels were significantly lower in highest baicalein concentration group. We conclude that baicalein can stimulate angiogenesis, though not fibre type-specific, in skeletal muscle and reduce the estrogen-related loss of fibre diameter and area in the skeletal muscle in rats. Therefore, a protective effect of baicalein on muscle cells can be assumed.

Hyperoside ameliorates glomerulosclerosis in diabetic nephropathy by downregulating miR-21

The purpose of this study was to investigate the therapeutic effects of hyperoside (Hyp) on glomerulosclerosis in diabetic nephropathy and its underlying mechanisms. Blood glucose, kidney mass, and renal function of mice were measured. Renal morphology was observed using hematoxylin and eosin, periodic acid - Schiff's, and Masson's trichrome stain. Fibronectin (FN) and collagen IV (COL IV) in kidney were determined by Western blot and immunohistochemical studies. Matrix metalloproteinases (MMP)-2 and -9 and tissue inhibitors of metalloproteinase (TIMP)-1 in renal tissues were detected on both the mRNA and protein levels. miRNA expression and artificial alterations by miRNA agomir transfection were evaluated to investigate the protective mechanism of Hyp in mesangial cells. Hyp effectively improved renal function and physiologic features of db/db mice. Hyp also ameliorated glomerulosclerosis by suppressing FN, COL IV, and TIMP-1 expressions and promoting MMP-9 and MMP-2 expressions. The change in MMP-9 mRNA expression was inconsistent with that in protein levels in kidney, indicating that there was a post-transcriptional regulation. Further exploration in vitro showed that miR-21 was downregulated by Hyp, increasing expression of its target, MMP-9. These results suggest that Hyp can ameliorate glomerulosclerosis in diabetic nephropathy by downregulating miR-21 to increase expression of its target, MMP-9.

The flavonoid baicalein rescues synaptic plasticity and memory deficits in a mouse model of Alzheimer's disease

Increasing evidence suggests that disruptions of synaptic functions correlate with the severity of cognitive deficit in Alzheimer's disease (AD). Our previous study demonstrated that baicalein enhances long-term potentiation (LTP) in acute rat hippocampal slices and improves hippocampus-dependent contextual fear conditioning in rats. Given that baicalein possess various biological activities, especially its effects on synaptic plasticity and cognitive function, we examined the effect of baicalein on synaptic function both in vitro and in vivo in AD model. The effect of baicalein on Aβ42 oligomer impaired LTP was investigated by electrophysiological methods. Baicalein was administered orally via drinking water to the APP/PS1 mice and sex- and age-matched wild-type mice. Treatment started at 5 months of age and mice were assessed for cognition and AD-like pathology at 7-month-old. Cognition was analyzed by Morris water maze test, fear conditioning test, and novel object recognition test. Changes in hippocampal 12/15 Lipoxygenase (12/15LO) and glycogen synthase kinase 3β (GSK3β) activity, Aβ production, tau phosphorylation, synaptic plasticity, and dendritic spine density were evaluated. Baicalein prevented Aβ-induced impairments in hippocampal LTP through activation of serine threonine Kinase (Akt) phosphorylation. Long-term oral administration of baicalein inhibited 12/15LO and GSK3β activity, reduced β-secretase enzyme (BACE1), decreased the concentration of total Aβ, and prevented phosphorylation of tau in APP/PS1 mice. Meanwhile, baicalein restored spine number, synaptic plasticity, and memory deficits. Our results strengthen the potential of the flavonoid baicalein as a novel and promising oral bioactive therapeutic agent that prevents memory deficits in AD.

Madecassoside ameliorates bleomycin-induced pulmonary fibrosis in mice through promoting the generation of hepatocyte growth factor via PPAR-γ in colon

BACKGROUND AND PURPOSE

Madecassoside has potent anti-pulmonary fibrosis (PF) effects when administered p.o., despite having extremely low oral bioavailability. Herein, we explored the mechanism of this anti-PF effect with regard to gut hormones.

EXPERIMENTAL APPROACH

A PF model was established in mice by intratracheal instillation of bleomycin. Haematoxylin and eosin stain and Masson's trichrome stain were used to assess histological changes in the lung. Quantitative-PCR and Western blot detected mRNA and protein levels, respectively, and cytokines were measured by ELISA. Small interfering RNA was used for gene-silencing. EMSA was applied to detect DNA-binding activity.

KEY RESULTS

Administration of madecassoside, p.o., but not its main metabolite madecassic acid, exhibited a direct anti-PF effect in mice. However, i.p. madecassoside had no anti-PF effect. Madecassoside increased the expression of hepatocyte growth factor (HGF) in colon tissues, and HGF receptor antagonists attenuated its anti-PF effect. Madecassoside facilitated the secretion of HGF from colonic epithelial cells by activating the PPAR-γ pathway, as shown by an up-regulation of PPAR-γ mRNA expression, nuclear translocation and DNA-binding activity both in vitro and in vivo. Also GW9662, a selective PPAR-γ antagonist, almost completely prevented the madecassoside-induced increased expression of HGF and amelioration of PF.

CONCLUSIONS AND IMPLICATIONS

The potent anti-PF effects induced by p.o. madecassoside in mice are not mediated by its metabolites or itself after absorption into blood. Instead, madecassoside increases the activity of PPAR-γ, which subsequently increases HGF expression in colonic epithelial cells. HGF then enters into the circulation and lung tissue to exert an anti-PF effect.

The Chinese Herbal Medicine Formula mKG Suppresses Pulmonary Fibrosis of Mice Induced by Bleomycin

Pulmonary fibrosis (PF) is a serious progressive lung disease and it originates from inflammation-induced parenchymal injury with excessive extracellular matrix deposition to result in the destruction of the normal lung architecture. Modified Kushen Gancao Formula (mKG), derived from traditional Chinese herbal medicine, has a prominent anti-inflammatory effect. The present study is to explore the inhibitory effects of mKG on bleomycin (BLM)-induced pulmonary fibrosis in mice. mKG significantly decreased pulmonary alveolitis, fibrosis scores, and interleukin-6 (IL-6), interleukin-17 (IL-17), transforming growth factor-β (TGF-β) and hydroxyproline (HYP) levels in lung tissue of mice compared with BLM treatment. It markedly alleviated the increase of HYP content in the lung tissues and pathologic changes of pulmonary fibrosis caused by BLM instillation. In conclusion, mKG has an anti-fibrotic effect and might be employed as a therapeutic candidate agent for attenuating pulmonary fibrosis.

The Analgesic and Antineuroinflammatory Effect of Baicalein in Cancer-Induced Bone Pain

Cancer-induced bone pain (CIBP) is a severe type of chronic pain. It is imperative to explore safe and effective analgesic drugs for CIBP treatment. Baicalein (BE), isolated from the traditional Chinese herbal medicine Scutellaria baicalensis Georgi (or Huang Qin), has been demonstrated to have anti-inflammatory and neuroprotective effects. In this study, we examined the effect of BE on CIBP and the mechanism of this effect. Intrathecal and oral administration of BE at different doses could alleviate the mechanical allodynia in CIBP rats. Intrathecal 100 μg BE could inhibit the production of IL-6 and TNF-α in the spinal cord of CIBP rats. Moreover, intrathecal 100 μg BE could effectively inhibit the activation of p-p38 and p-JNK MAPK signals in CIBP rats. The analgesic effect of BE may be associated with the inhibition of the expression of the inflammatory cytokines IL-6 and TNF-α and through the activation of p-p38 and p-JNK MAPK signals in the spinal cord. These findings suggest that BE is a promising novel analgesic agent for CIBP.

The Anti-fibrotic Effects and Mechanisms of MicroRNA-486-5p in Pulmonary Fibrosis

To identify microRNAs (miRNAs, miRs) with potential roles in lung fibrogenesis, we performed genome-wide profiling of miRNA expression in lung tissues from a silica-induced mouse model of pulmonary fibrosis using microarrays. Seventeen miRNAs were selected for validation via qRT-PCR based on the fold changes between the silica and the control group. The dysregulation of five miRNAs, including miR-21, miR-455, miR-151-3p, miR-486-5p and miR-3107, were confirmed by qRT-PCRs in silica-induced mouse model of pulmonary fibrosis and were also confirmed in a bleomycin (BLM)-induced mouse lung fibrosis. Notably, miR-486-5p levels were decreased in the serum samples of patients with silicosis, as well as in the lung tissues of patients with silicosis and idiopathic pulmonary fibrosis (IPF). In addition, as determined by luciferase assays and Western blotting, SMAD2, a crucial mediator of pulmonary fibrosis, was identified to be one of target genes of miR-486-5p. To test the potential therapeutic significance of this miRNA, we overexpressed miR-486-5p in animal models. At day 28, miR-486-5p expression significantly decreased both the distribution and severity of lung lesions compared with the silica group (P < 0.01). In addition, miR-486-5p had a similar effect in the BLM group (P < 0.001). These results indicate that miR-486-5p may inhibit fibrosis.

Effect of glycosides based standardized fenugreek seed extract in bleomycin-induced pulmonary fibrosis in rats: Decisive role of Bax, Nrf2, NF-κB, Muc5ac, TNF-α and IL-1β

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive multifactorial disease with limited therapeutic options. Glycosides based standardized fenugreek seed extract (SFSE-G) possesses potent anti-inflammatory and anti-oxidant property.

AIM

To evaluate the efficacy of SFSE-G against bleomycin (BLM) induced pulmonary fibrosis by assessing behavioral, biochemical, molecular and ultrastructural changes in the laboratory rats.

MATERIALS AND METHODS

IPF was induced in male Sprague-Dawley rats by single intratracheal BLM (6IU/kg) injection followed by SFSE-G (5, 10, 20 and 40mg/kg, p.o.) or methylprednisolone (10mg/kg, p.o.) treatment for 28day. Various parameters were analyzed in lung and bronchoalveolar lavage fluid (BALF) after 14 and 28days of the drug treatment.

RESULTS

SFSE-G (20 and 40mg/kg, p.o.) administration significantly prevented the BLM induced alteration in body weight, lung index, lung function test and hematology. The altered total and differential cell count in BALF and blood was significantly prevented by SFSE-G treatment. The decreased peripheral blood oxygen content after BLM instillation was significantly increased by SFSE-G treatment. SFSE-G significantly enhanced the BALF and lung antioxidant status, through modulating the SOD, GSH, T-AOC, MDA, NO level and Nrf2, HO-1 mRNA expression. There was a significant reduction in lung 5-HT level by SFSE-G treatment. The altered mRNA expression of biomarkers of lung inflammation (TNF-α, IL-1β, IL-6 and IL-8), fibrosis (TGF-β, collagen-1, ET-1, Muc5ac, NF-κB, VEGF, Smad-3) and apoptosis (Bax, Bcl-2 and Caspase-3) were significantly prevented by SFSE-G treatment. BLM induced histological inflammatory and fibrotic insult in the lung were reduced by SFSE-G treatment. It also ameliorated BLM induced lung ultrastructural changes as observed by transmission electron microscopic studies. However, administration of SFSE-G (5mg/kg, p.o.) failed to show any protective effect against BLM-induced PF whereas SFSE-G (10mg/kg, p.o.) showed significant amelioration in BLM-induced PF except lung function test, BALF and lung antioxidant level.

CONCLUSION

SFSE-G showed anti-fibrotic efficacy executed through induction of Nrf2, which in turn may modulate anti-inflammatory molecules, inhibit fibrogenic molecules and decreased apoptosis to ameliorate BLM induced pulmonary fibrosis.

miR-21 overexpression enhances TGF-β1-induced epithelial-to-mesenchymal transition by target smad7 and aggravates renal damage in diabetic nephropathy

Epithelial-to-mesenchymal transition (EMT) plays an important role in renal interstitial fibrosis (RIF) with diabetic nephropathy (DN). Smad7 (a inhibitory smad), a downstream signaling molecules of TGF-β1, represses the EMT. The physiological function of miR-21 is closely linked to EMT and RIF. However, it remained unclear whether miR-21 over-expression affected TGF-β1-induced EMT by regulating smad7 in DN. In this study, real-time RT-PCR, cell transfection, luciferase reporter gene assays, western blot and confocal microscope were used, respectively. Here, we found that miR-21 expression was upregulated by TGF-β1 in time- and concentration -dependent manner. Moreover, miR-21 over-expression enhanced TGF-β1-induced EMT(upregulation of a-SMA and downregulation of E-cadherin) by directly down-regulating smad7/p-smad7 and indirectly up-regulating smad3/p-smad3, accompanied by the decrease of Ccr and the increase of col-IV, FN, the content of collagen fibers, RTBM, RTIAW and ACR. Meantime, the siRNA experiment showed that smad7 can directly regulate a-SMA and E-cadherin expression. More importantly, miR-21 inhibitor can not only inhibit EMT and fibrosis but also ameliorate renal structure and function. In conclusion, our results demonstrated that miR-21 overexpression can contribute to TGF-β1-induced EMT by inhibiting target smad7, and that targeting miR-21 may be a better alternative to directly suppress TGF-β1-mediated fibrosis in DN.

Baicalein ameliorates inflammatory-related apoptotic and catabolic phenotypes in human chondrocytes

Osteoarthritis (OA), characterized by progressive destruction of articular cartilage, is the most common form of human arthritis and a major concern for aging societies worldwide. In OA, pro-inflammatory cytokines such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α can trigger the caspase cascade to promote apoptosis and activate NF-κB to induce catabolic factors in chondrocytes. Here, the anti-apoptotic and anti-catabolic effects of baicalein on human OA chondrocytes treated by a mixture of IL-1β and TNF-α (IT) were investigated in vitro. In cultured chondrocytes, baicalein pretreatment attenuated apoptosis in a concentration-dependent manner in response to IT stimulation. Mechanistically, the anti-apoptotic effects of baicalein result from inhibition of nitric oxide production and downstream caspase signaling pathway. Moreover, administration of baicalein significantly reduced matrix metalloproteinase (MMP) 3 and MMP13 secretion in chondrocytes stimulated with IT. The anti-catabolic effects of baicalein were further demonstrated by the recovery of the glycosaminoglycan and type II collagen (COLII) deposition by histological analysis in IT-treated mouse articular cartilage explants. These findings suggest that baicalein might be a promising novel therapeutic agent for OA by virtue of its suppression of apoptosis and MMP secretion in OA chondrocytes.