Baicalin suppresses expression of TLR2/4 and NF-κB in chlamydia trachomatis-infected mice

Alternative strategies for Chlamydia treatment: Promising non-antibiotic approaches

Chlamydia is an obligate intracellular bacterium where most species are pathogenic and infectious, causing various infectious diseases and complications in humans and animals. Antibiotics are often recommended for the clinical treatment of chlamydial infections. However, extensive research has shown that antibiotics may not be sufficient to eliminate or inhibit infection entirely and have some potential risks, including antibiotic resistance. The impact of chlamydial infection and antibiotic misuse should not be underestimated in public health. This study explores the possibility of new therapeutic techniques, including a review of recent studies on preventing and suppressing chlamydial infection by non-antibiotic compounds.

Drug Candidates for Autoimmune Diseases

Most of the immunosuppressive drugs used in the clinic to prevent organ rejection or to treat autoimmune disorders were originally isolated from fungi or bacteria. Therefore, in addition to plants, these are valuable sources for identification of new potent drugs. Many side effects of established drugs limit their usage and make the identification of new immunosuppressants necessary. In this review, we present a comprehensive overview of natural products with potent anti-inflammatory activities that have been tested successfully in different models of chronic inflammatory autoimmune diseases. Some of these candidates already have passed first clinical trials. The anti-inflammatory potency of these natural products was often comparable to those of established drugs, and they could be used at least in addition to standard therapy to reduce their dose to minimize unwanted side effects. A frequent mode of action is the inhibition of classical inflammatory signaling pathways, such as NF-κB, in combination with downregulation of oxidative stress. A drawback for the therapeutic use of those natural products is their moderate bioavailability, which can be optimized by chemical modifications and, in addition, further safety studies are necessary. Altogether, very interesting candidate compounds exist which have the potential to serve as starting points for the development of new immunosuppressive drugs.

Baicalin ameliorates Mycoplasma gallisepticum-induced lung inflammation in chicken by inhibiting TLR6-mediated NF-κB signalling

1. Mycoplasma gallisepticum (MG) causes severe lung inflammation and cell damage by activating toll-like receptor (TLR) signalling, the nuclear factor-kappaB (NF-κB) pathway and pro-inflammatory cytokine gene expression. Baicalin (BA) is a flavonoid extracted from Scutellaria baicalensis, which possesses anti-inflammatory and anti-bacterial properties. This study investigated the effect of BA in MG-induced lung inflammation and its potential mechanism in MG-infected chicken embryo lungs and DF-1 cells.2. The histopathological examination result showed that BA treatment alleviated MG-induced lung pathological changes. In addition, CCK-8 and cell cycle assays showed that BA treatment inhibited MG-induced cell proliferation and cell cycle progression in DF-1 cells.3. The ELISA and RT-qPCR results demonstrated that BA treatment decreased the expression of interleukin-1beta (IL-1β), IL-6, and tumour necrosis factor-alpha (TNF-α) both in MG-infected chicken embryo lungs and DF-1 cells.4. The results revealed that BA inhibited mRNA expression levels of toll-like receptor-6 (TLR6), myeloid differentiation primary response gene-88 (MyD88) and nuclear factor-κB (NF-κB), and the nuclear translocation of NF-κB-p655. In conclusion, the results showed that BA has a protective effect against MG-induced lung inflammation in chicken by inhibiting the TLR6-mediated NF-κB signalling.

Immunological regulatory effect of flavonoid baicalin on innate immune toll-like receptors

As an essential component of the innate immune system, Toll-like receptors (TLRs) are a family of well-recognized ligand-binding receptors found in various organisms and initiate host immune responses. Activation of TLRs signaling pathways lead to the induction of numerous genes that function in host defense. Baicalin is a natural compound from the dry raw root of Scutellaria baicalensis (S. baicalensis) and it has been found to exhibit several pharmaceutical actions, such as anti-inflammation, anti-tumor and antivirus. These biological activities are mainly related to the regulatory effect of baicalin on the host immune response. In this review, we provide an overview of the regulation of baicalin on TLRs signaling pathways in various pathological conditions, and highlight potential targets for the development of the regulatory effect of natural compound from traditional Chinese medicine on innate immune system.

Low n-6/n-3 PUFA ratio improves inflammation and myocardial ischemic reperfusion injury

This study investigated the potential effect of n-6/n-3 polyunsaturated fatty acids (PUFA) on inflammation and myocardial ischemic reperfusion injury (MIRI) in rats, together with the underlying protective mechanisms, and screen out most effective ratio of n-6/n-3 within limits. The rats with pre-infarct treatment were distributed among 5 groups according to the n-6/n-3 ratio (36:1; 1:1, 5:1, 10:1, 50:1); for the post-infarct treatment, the rats were distributed among 6 groups, including the control group (36:1) which was subjected to a sham procedure; the model group (36:1); and 4 test groups (n-6/n-3 ratio: 1:1, 5:1, 10:1, 50:1). All of the rats were fed a purple perilla seed oil and safflower oil-based fatty emulsion. The serum levels of monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α were determined using enzyme-linked immunosorbent assay. Staining with triphenyl tetrazolium chloride, hematoxylin and eosin, or Masson's trichrome was performed for histological examination. Cardiomyocyte apoptosis was examined by TUNEL assay. Western blotting was performed to examine the expression levels of apoptosis-related proteins and signaling pathway proteins. Our data indicate that in both the pre-infarct treatment and post-infarct treatment, low ratios of n-6/n-3 PUFAs significantly inhibited the levels of serum inflammatory factors, the infarct size of MIRI rats, number of cardiomyocytes undergoing apoptosis, and the expression levels of caspase-3, Bcl-2, and Bax in the MIRI group. Thus a low ratio of n-6/n-3 PUFAs ameliorates inflammation and myocardial ischemic reperfusion injury.

Protective Effect of UP446 on Ligature-Induced Periodontitis in Beagle Dogs

Periodontal disease is an inflammatory disease of the gum caused by a formation of a plaque that triggers immune responses and inflammation leading to the destruction of tissues surrounding and supporting the teeth. Chronic usage of synthetic chemicals and antibiotics is limited by undesired adverse events to the host. A botanical composition (UP446), which consists primarily of bioflavonoids such as baicalin from roots of Scutellaria baicalensis and catechins from heartwoods of Acacia catechu, was evaluated for its effect on ligature-induced periodontal disease in beagle dogs. Disease model was induced in 20 male and female dogs. After a 12-week induction of periodontitis, animals were assigned to a placebo, positive control (doxycycline), and two treatment groups consisting of five animals each. The placebo group was only administrated to normal dog chow (25 g/kg/day). In the doxycycline treatment group, animals were fed a normal diet (25 g/kg/day) and doxycycline (5 mg/kg) was orally administrated every day. Treatment of UP446 was done by feeding the regular diet formulated with 0.1% and 0.2% of UP446 by weight. Clinical indices such as plaque index (PI), gingival index (GI), clinical attachment level (CAL), probing pocket depth (PPD), and bleeding on probing (BoP) were measured every two weeks for 12 weeks. UP446 administered to beagle dogs for 12 weeks at 0.1% and 0.2% resulted in statistically significant reductions in gingivitis, pocket depth, loss of attachment, and gum bleeding. UP446 could potentially be used alone or as an adjunct with other oral hygiene preparations for periodontal disease in both human and companion animals.

Baicalin alleviates radiation-induced epithelial-mesenchymal transition of primary type II alveolar epithelial cells via TGF-β and ERK/GSK3β signaling pathways

BACKGROUND

Radiation therapy is commonly used to treat thoracic malignancies. However, it may lead to severe lung pneumonitis and ultimately fibrosis. Irradiation has been reported to increase epithelial-mesenchymal transition (EMT) of type II alveolar epithelial cells (AEC), which play an important role in pulmonary fibrosis. The transforming growth factor-β (TGF-β) and ERK/glycogen synthase kinase 3β (GSK3β) pathways are critically involved in radiation-induced EMT. In the present study, we investigated whether baicalin was a novel therapeutic candidate for radiation-induced EMT in type II AEC.

METHODS

Primary type II AEC were isolated and treated with ⁶⁰Co γ-rays and a series doses of baicalin (2μM, 10μM and 50μM). The ultrastructure and morphology changes were observed by transmission electron microscopy and optical microscopy, respectively. Protein expression was determined by western blotting analysis. Immunofluorescence staining was performed to detect the nuclear translocation of Snail.

RESULTS

After irradiation, type II AEC displayed a mesenchymal-like morphology accompanied by a decrease in E-cadherin expression, an increase in the expression of Vimentin and α-SMA. Nuclear translocation of Snail, the activation of TGF-β/Smad pathway, and the inactivation of GSK3β were prominent in radiation-treated cells. Baicalin significantly attenuated the effects of radiation on type II AEC.

CONCLUSIONS

Baicalin may a useful radioprotective agent through suppressing the EMT of type II AEC.

Comparative pharmacokinetic study of baicalin and its metabolites after oral administration of baicalin and Chaiqin Qingning capsule in normal and febrile rats

An accurate, precise, selective, and sensitive high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) method was developed for the simultaneous determination of baicalin and its metabolite, baicalein 6-O-glucopyranuronoside, in normal and febrile rats plasma. Two analytes, along with hesperidin as an internal standard, were determined by multiple reactions monitoring (MRM) operated in the positive electrospray ionization (ESI) mode. Chromatographic separation was performed on an Agilent ZORBAX Extend-C18 column (100mm×2.10mm, 3.5μm) with a mobile phase of 0.1% formic acid solution and acetonitrile at a flow rate of 0.6mL/min. The calibration curves showed good linearity (r≥0.9974) with the concentration ranges of 2.000-2000ngmL^-1 for baicalin and baicalein 6-O-glucopyranuronoside. The inter- and intra-day accuracies (relative error, RE%) were between -6.62% and 6.75%, and the precisions (relative standard deviation, RSD%) were less than 9.09% for quality control samples (QCs). The method also possessed good selectivity, recovery and stability, and was successfully applied to a comparative pharmacokinetic study of baicalin and baicalein 6-O-glucopyranuronoside in normal and febrile rats after oral administration of baicalin and Chaiqin Qingning capsule.

Baicalin attenuates bleomycin-induced pulmonary fibrosis via adenosine A2a receptor related TGF-β1-induced ERK1/2 signaling pathway

BACKGROUND

Baicalin has been reported to have anti-fibrosis effect; however, its mechanism still remains to be elucidated. Adenosine A2a receptor (A2aR) is a novel inflammation regulator, and transforming growth factor-β1 (TGF-β1)-induced extracellular signal regulated kinase1/2 (ERK1/2) signaling pathway plays an important role in idiopathic pulmonary fibrosis (IPF). This study was to explore the relationship of A2aR and TGF-β1-induced ERK1/2 in bleomycin (BLM)-induced pulmonary fibrosis in mice, and to investigate whether A2aR mediate the anti-fibrosis effect of Baicalin on BLM-induced pulmonary fibrosis.

METHODS

The A2aR-/- and A2aR+/+ mice were respectively divided into three groups: control group, model group, baicalin group. Pulmonary fibrosis was induced in mice of model groups by intratracheal instillation of bleomycin, and baicalin was administered in mice of baicalin groups daily for 28 days. Histopathological and ultrastructural changes of lung tissues were evaluated. Lung coefficient and the levels of hydroxyproline (HYP) in lung tissues were measured at the same time. The levels of serum TGF-β1 were measured by ELISA. The expression of TGF-β1, ERK1/2, p-ERK1/2 and A2aR were detected by western blot and immunohistochemical staining techniques.

RESULTS

Severe lung fibrosis was observed in the bleomycin-treated mice on day 28. The histopathological findings and collagen content of lung tissues were much severer/higher in A2aR-/- mice than in A2aR+/+ mice. We also showed that TGF-β1 and p-ERK1/2 were upregulated in bleomycin-treated mice and expressed higher in A2aR-/- mice compared to A2aR+/+ mice. Besides, bleomycin-treated A2aR+/+ mice had increased A2aR level in lungs. However, long-term treatment with baicalin in A2aR-/- and A2aR+/+ mice significantly ameliorated the histopathological changes in lungs. Moreover, Increased TGF-β1 and p-ERK1/2 expressions in bleomycin-treated A2aR-/- and A2aR+/+ mice were obviously diminished by baicalin. The baicalin-treated A2aR-/- mice had severer lung fibrosis and higher expressions of TGF-β1 and p-ERK1/2 than A2aR+/+ mice. Baicalin has also upregulated the expression of A2aR in A2aR+/+ mice.

CONCLUSIONS

Genetic inactivation of A2aR exacerbated the pathological processes of bleomycin-induced pulmonary fibrosis. Together, baicalin could inhibit BLM-induced pulmonary fibrosis by upregulating A2aR, suggesting A2aR as a therapeutic target of baicalin for the treatment of pulmonary fibrosis.

Jeju seaweeds suppress lipopolysaccharide-stimulated proinflammatory response in RAW 264.7 murine macrophages

OBJECTIVE

To investigate the anti-inflammatory effects of Jeju seaweeds on macrophage RAW 264.7 cells under lipopolysaccharide (LPS) stimulation.

METHODS

Ethyl acetate fractions were prepared from five different types of Jeju seaweeds, Dictyopteris divaricata (D. divaricata), Dictyopteris prolifera (D. prolifera), Prionitis cornea (P. cornea), Grateloupia lanceolata (G. lanceolata), and Grateloupia filicina (G. filicina). They were screened for inhibitory effects on proinflammatory mediators and cytokines such as nitric oxide (NO), prostaglandin E2, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6).

RESULTS

Our results revealed that D. divaricata, D. prolifera, P. cornea, G. lanceolata, and G. filicina potently inhibited LPS-stimulated NO production (IC50 values were 18.0, 38.36, 38.43, 32.81 and 37.14 µg/mL, respectively). Consistent with these findings, D. divaricata, D. prolifera, P. cornea, and G. filicina also reduced the LPS-induced and prostaglandin E2 production in a concentration-dependent manner. Expectedly, they suppressed the expression of inducible NO synthase and cyclooxygenase-2 at the protein level in a dose-dependent manner in the RAW 264.7 cells, as determined by western blotting. In addition, the levels of TNF-α and IL-6, released into the medium, were also reduced by D. divaricata, D. prolifera, P. cornea, G. lanceolata, and G. filicina in a dose-dependent manner (IC50 values for TNF-α were 16.11, 28.21, 84.27, 45.52 and 74.75 µg/mL, respectively; IC50 values for IL-6 were 37.35, 80.08, 103.28, 62.53 and 84.28 µg/mL, respectively). The total phlorotannin content was measured by the Folin-Ciocalteu method and expressed as phloroglucinol equivalents. The content was 92.0 µg/mg for D. divaricata, 151.8 µg/mg for D. prolifera, 57.2 µg/mg for P. cornea, 53.0 µg/mg for G. lanceolata, and 40.2 µg/mg for G. filicina.

CONCLUSIONS

Thus, these findings suggest that Jeju seaweed extracts have potential therapeutic applications for inflammatory responses.

The protective effect of baicalin against renal ischemia-reperfusion injury through inhibition of inflammation and apoptosis

Background

Renal ischemia-reperfusion injury (IRI) increases the rates of acute kidney failure, delayed graft function, and early mortality after kidney transplantation. The pathophysiology involved includes oxidative stress, mitochondrial dysfunction, and immune-mediated injury. The anti-oxidation, anti-apoptosis, and anti-inflammation properties of baicalin, a flavonoid glycoside isolated from Scutellaria baicalensis, have been verified. This study therefore assessed the effects of baicalin against renal IRI in rats.

Methods

Baicalin was intraperitoneally injected 30 min before renal ischemia. Serum and kidneys were harvested 24 h after reperfusion. Renal function and histological changes were assessed. Markers of oxidative stress, the Toll-like receptor (TLR)2 and TLR4 signaling pathway, mitochondrial stress, and cell apoptosis were also evaluated.

Results

Baicalin treatment decreased oxidative stress and histological injury, and improved kidney function, as well as inhibiting proinflammatory responses and tubular apoptosis. Baicalin pretreatment also reduced the expression of TLR2, TLR4, MyD88, p-NF-κB, and p-IκB proteins, as well as decreasing caspase-3 activity and increasing the Bcl-2/Bax ratio.

Conclusions

Baicalin may attenuate renal ischemia-reperfusion injury by inhibiting proinflammatory responses and mitochondria-mediated apoptosis. These effects are associated with the TLR2/4 signaling pathway and mitochondrial stress.

A fraction of stem bark extract of Entada africana suppresses lipopolysaccharide-induced inflammation in RAW 264.7 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Entada africana is a plant used in African traditional medicine for the treatment of stomachache, fever, liver related diseases, wound healing, cataract and dysentery.

AIMS OF THE STUDY

This study aimed at evaluating the anti-inflammatory activity of fractions of the stem bark extract of the plant using lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 macrophages model.

MATERIALS AND METHODS

The crude extract was prepared using the mixture CH2Cl2/MeOH (1:1, v/v) and fractionated by flash chromatography using solvents of increasing polarity to obtain five different fractions. The effects of the fractions on the cells viability were studied by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and their inhibitory activity against LPS-induced nitric oxide (NO) production screened by Griess test. The most active fraction was further investigated for its effects on reactive oxygen species (ROS) production using flux cytometry, the expression of inducible nitric oxide synthase (iNOS), pro-and anti-inflammatory cytokines (IL1β, TNFα, IL6, IL10 and IL13) by RT-PCR, and the activity of the enzyme p38 MAPK kinase by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The fractions presented no significant effect on the viability of macrophages at 100 μg/ml after 24h incubation. The CH2Cl2/MeOH 5% (Ea5) fraction was found to be the most potent in inhibiting NO production with a half inhibition concentration (IC50)=18.36 μg/ml, and showed the highest inhibition percentage (89.068%) in comparison with Baicalin (63.34%), an external standard at 50 μg/ml. Ea5, as well as Baicalin significantly (P<0.05) inhibited the expression of TNFα, IL6 and IL1β mRNA, attenuated mRNA expression of inducible NO synthase in a concentration-dependent manner, stimulated the expression of anti-inflammatory cytokines (IL10 and IL13), and showed a 30% inhibition of the activity of p38 MAPK kinase.

CONCLUSION

The results of the present study indicate that the fraction Ea5 of Entada africana possesses most potent in vitro anti-inflammatory activity and may contain compounds useful as a therapeutic agent in the treatment of inflammatory related diseases cause by over-activation of macrophages.

Immunomodulaton and attenuation of lethal influenza A virus infection by oral administration with KIOM-C

Herbal medicine is used to treat many conditions such as asthma, eczema, premenstrual syndrome, rheumatoid arthritis, migraine, headaches, menopausal symptoms, chronic fatigue, irritable bowel syndrome, cancer, and viral infections such as influenza. In this study, we investigated the antiviral effect of KIOM-C for the treatment of influenza A virus infection. Our results show that oral administration of KIOM-C conferred a survival benefit to mice infected with the 2009 pandemic H1N1 [A(H1N1)pdm09] virus, and resulted in a 10- to 100-fold attenuation of viral replication in ferrets in a dose-dependent manner. Additionally, oral administration of KIOM-C increased the production of antiviral cytokines, including IFN-γ and TNF-α, and decreased levels of pro-inflammatory cytokines (IL-6) and chemokines (KC, MCP-1) in the Bronchoalveolar lavage fluid (BALF) of A(H1N1)pdm-infected mice. These results indicate that KIOM-C can promote clearance of influenza virus in the respiratory tracts of mice and ferrets by modulating cytokine production in hosts. Taken together, our results suggest that KIOM-C is a potential therapeutic compound mixture for the treatment of influenza virus infection in humans.

Role of the Toll Like receptor (TLR) radical cycle in chronic inflammation: possible treatments targeting the TLR4 pathway

Activation of the Toll-like receptor 4 (TLR4) complex, a receptor of the innate immune system, may underpin the pathophysiology of many human diseases, including asthma, cardiovascular disorder, diabetes, obesity, metabolic syndrome, autoimmune disorders, neuroinflammatory disorders, schizophrenia, bipolar disorder, autism, clinical depression, chronic fatigue syndrome, alcohol abuse, and toluene inhalation. TLRs are pattern recognition receptors that recognize damage-associated molecular patterns and pathogen-associated molecular patterns, including lipopolysaccharide (LPS) from gram-negative bacteria. Here we focus on the environmental factors, which are known to trigger TLR4, e.g., ozone, atmosphere particulate matter, long-lived reactive oxygen intermediate, pentachlorophenol, ionizing radiation, and toluene. Activation of the TLR4 pathways may cause chronic inflammation and increased production of reactive oxygen and nitrogen species (ROS/RNS) and oxidative and nitrosative stress and therefore TLR-related diseases. This implies that drugs or substances that modify these pathways may prevent or improve the abovementioned diseases. Here we review some of the most promising drugs and agents that have the potential to attenuate TLR-mediated inflammation, e.g., anti-LPS strategies that aim to neutralize LPS (synthetic anti-LPS peptides and recombinant factor C) and TLR4/MyD88 antagonists, including eritoran, CyP, EM-163, epigallocatechin-3-gallate, 6-shogaol, cinnamon extract, N-acetylcysteine, melatonin, and molecular hydrogen. The authors posit that activation of the TLR radical (ROS/RNS) cycle is a common pathway underpinning many "civilization" disorders and that targeting the TLR radical cycle may be an effective method to treat many inflammatory disorders.

Baicalin attenuates proinflammatory cytokine production in oxygen-glucose deprived challenged rat microglial cells by inhibiting TLR4 signaling pathway

Baicalin, a flavonoid compound isolated from Scutellariae radix, has been shown to possess a number of pharmacological effects. The aim of the present study was to observe the inhibitory effects of baicalin on the activation of microglial cells induced by oxygen-glucose deprivation (OGD) and the specific mechanisms by which these effects are mediated. Cultured rat primary microglial cells were exposed to baicalin at final concentrations of 10 μg/ml, 20 μg/ml and 40 μg/ml during 4h of OGD. The effects of baicalin on (i) cell viability; (ii) secretion of proinflammatory cytokines; (iii) Tlr4 mRNA expression; (iv) p-c-jun, p-ERK1/2, p-JNK, p-p38, TRAF6 and p-IκB-α levels; and (v) co-localization of TLR4 and MyD88 were evaluated using the Cell Counting Kit-8 (CCK-8), enzyme-linked immunosorbent assays (ELISA), reverse transcription-polymerase chain reaction (RT-PCR), western blot and double-labeled immunofluorescence staining, respectively. OGD increased cell viability and release of TNF-α, IL-1β, IL-6 and IL-8, these effects were suppressed by baicalin. Baicalin also attenuated the OGD-induced increases in Tlr4 mRNA expression. In addition, high dose of baicalin reduced TRAF6 levels remarkably. Furthermore, baicalin also downregulated phosphorylation of IκB-α, c-jun, ERK1/2, JNK, p38 and inhibited the OGD-induced transfer of MyD88 from cytoplasm to membrane in microglial cells. The results show that baicalin can inhibit OGD-induced production of inflammatory factors in microglial cells by attenuating inflammatory factors and regulating the TLR4 signaling pathways.