Induction of TGF-β and IL-10 production in dendritic cells using astilbin to inhibit dextran sulfate sodium-induced colitis

Astilbin Attenuates Cadmium-Induced Adipose Tissue Damage by Inhibiting NF-κB Pathways and Regulating the Expression of HSPs in Chicken

Cadmium (Cd) can damage tissues by inducing oxidative stress, lymphocyte infiltration, and inflammation in these sites. Meanwhile, astilbin (Ast) is an antioxidant agent. At present, only a few mechanisms of Cd-induced adipose tissue damage have been described. Herein, we assessed the potential protective effects and the molecular mechanism underlying the antioxidant properly of Ast after Cd intake in chicken adipose tissue. In this study, a total of 160 7-day-old roosters were randomly divided into four groups. Roosters were fed with a basic diet (C group), Ast 40 mg/kg (Ast group), CdCl₂ 150 mg/kg + Ast 40 mg/kg (Cd/Ast group), and CdCl₂ 150 mg/kg (Cd group) for 60 days. We found that Cd intake changed the morphology and structure of adipose tissues and decreased the expression of several antioxidants, including total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and total antioxidant capacity (T-AOC), but increased those of oxidative stress markers including malondialdehyde (MDA), inducible nitric oxide synthase (iNOS), NO, and H2O2. Cd further activated the nuclear factor kappa B (NF-κB) signaling pathway and increased the expression of the inflammation-related mediators, interleukin 1beta (IL-1β), interleukin 6 (IL-6), interleukin 8 (IL-8), interleukin 10 (IL-10), cyclooxygenase-2 (COX-2), iNOS, prostaglandin E synthase (PTGES), tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ). Cd-induced oxidative stress upregulated the expression of three heat shock proteins (HSPs), including HSP27, HSP70, and HSP90. Summarily, Cd causes oxidative stress-mediated tissue damage by activating the NF-κB pathway, promoting inflammation and upregulating the expression of HSPs. However, Ast supplementation modulates oxidative stress in adipose tissue by inhibiting inflammation mediated by the NF-κB pathway and regulating the expression of HSPs.

Astilbin Activates the Reactive Oxidative Species/PPARγ Pathway to Suppress Effector CD4+ T Cell Activities via Direct Binding With Cytochrome P450 1B1

Astilbin, as a compound of flavonoids, exerts anti-inflammation, antioxidation, and immune-suppression activities. Decreased activation of NF-κB and p38 MAPK and increased activation of SOCS3 and AMPK have been found in astilbin-treated cells. However, what molecules are docked by astilbin to initiate signaling cascades and result in functional changes remains unknown. In the study, we found that astilbin efficiently suppressed TNF-α production and increased CCR9 and CD36 expression of CD4⁺ T cells. In vivo administration of astilbin repressed the occurrence of type 1 diabetes mellitus in non-obese diabetic mice. The PPARγ/SOCS3, PPARγ/PTEN, and PPARγ/AMPK signaling pathways were substantially activated and played key roles in astilbin-induced downregulation of CD4⁺ T cell functions. Transcriptome sequencing results confirmed the changes of signaling molecules involved in the immune system, inflammatory responses, and indicated variations of multiple enzymes with oxidant or antioxidant activities. Astilbin directly induced cytoplasmic ROS production of CD4⁺ T cells ex vivo, but had no effects on mitochondrial ROS and mitochondrial weight. When cellular ROS was depleted, astilbin-treated CD4⁺ T cells remarkably reversed the expression of TNF-α, IFN-γ, CCR9, CD36, and signaling molecules (PPARγ, PTEN, p-AMPK, and SOCS3). Based on bioinformatics, two P450 enzymes (CYP1B1 and CYP19A1) were selected as candidate receptors for astilbin. CYP1B1 was identified as a real docking protein of astilbin in ROS production by AutoDock Vina software analysis and surface plasmon resonance assay. Collectively, astilbin downregulates effector CD4⁺ T cell activities via the CYP1B1/ROS/PPARγ pathway, which firmly supports its potential use in the treatment of inflammation.

Astilbin combined with lipopolysaccharide induces IL-10-producing regulatory B cells via the STAT3 signalling pathway

OBJECTIVES

Astilbin exerts immunoregulatory activities and plays anti-inflammatory effects in inflammation-associated diseases. IL-10-producing B cells are the major subset of regulatory B cells (Bregs) and inhibit inflammation and autoimmune diseases. This study aimed to analyse the inducing effect of astilbin on Bregs and investigate the involved molecular mechanisms.

METHODS

The frequencies and activities of IL-10-producing Bregs were observed using the co-treatment of astilbin and lipopolysaccharide (LPS) ex vivo. The protective effect of astilbin/LPS-induced Bregs on dextran sulphate sodium (DSS)-induced colitis was confirmed in vivo. The molecular signalling events of Breg induction were checked via Western blot. CD40-/- and toll-like receptor (TLR) 4-/- B cells were treated with astilbin/LPS to determine the modulatory role of CD40 or TLR4 on astilbin/LPS-induced Bregs.

RESULTS

Although astilbin alone could not affect Bregs, the co-treatment of astilbin and LPS remarkably induced CD19+ CD1dhi and CD19+ TIM-1+ cells which produced IL-10 ex vivo. Colonic CD19+ CD1dhi and CD19+ TIM-1+ cells were also increased in astilbin-treated mice with DSS-induced colitis. The adoptive transfer of CD19+ TIM-1+ cells pre-induced by astilbin/LPS directly suppressed the progression of DSS-induced colitis. Combined astilbin and LPS stimulated the STAT3 activation of CD19+ TIM-1+ cells but had no effects on SOCS3, AKT, NF-κB, Erk, JNK nor P38. Inhibiting the STAT3 phosphorylation of CD19+ TIM-1+ cells abolished Breg induction by astilbin/LPS. Furthermore, Breg induction was weakened in CD40-/- B cells with the decrease in STAT3 activation, but had disappeared in TLR4-/- B cells with no STAT3 activation, thereby confirming the indispensable role of TLR4 signalling in the induction of IL-10-producing Bregs.

CONCLUSIONS

This study reports the new immunoregulatory role of astilbin for promoting IL-10-producing B cells and suggests the possible use of astilbin in the therapy of inflammatory diseases.

Phytochemicals affect T helper 17 and T regulatory cells and gut integrity: implications on the gut-bone axis

The pathology of osteoporosis is multifactorial, but a growing body of evidence supports an important role of the gut-bone axis, especially in bone loss associated with menopause, rheumatoid arthritis, and periodontal disease. Aberrant T cell responses favoring an increase in the ratio of T helper 17 cells to T regulatory cells play a critical role in the underlying etiology of this bone loss. Many of the dietary phytochemicals known to have osteoprotective activity such as flavonoids, organosulfur compounds, phenolic acids, as well as the oligosaccharides also improve gut barrier function and affect T cell differentiation and activation within gut-associated lymphoid tissues and at distal sites. Here, we examine the potential of these phytochemicals to act as prebiotics and immunomodulating agents, in part targeting the gut to mediate their effects on bone.

Study on Anti-Inflammatory Effect and Major Anti-Inflammatory Components of PSORI-CM02 by Zebrafish Model

PSORI-CM02 is an optimization formula of PSORI-CM01, which is a clinical herbal formula for the treatment for psoriasis in the Guangdong Provincial Hospital of Chinese Medicine. Previous research indicates that it plays a critical role in anti-inflammation and immunoregulation. Rhizoma smilacis glabrae (RSG) is one herbal medicine of PSORI-CM02, whose effective anti-inflammatory component is astilbin. This study aims to test the anti-inflammatory and immunoregulation effects of astilbin as well as RSG in PSORI-CM02, and we, respectively, used the CuSO₄-induced neutrophil-specific transgenic zebrafish model Tg(mpx: EGFP) and the melanin allele mutated Albino strain zebrafish model to visualize the effects of neutrophil recruitment and macrophage phagocytosis. Our data indicated that both PSORI-CM02 and astilbin had anti-inflammatory effects, leading to a reduction in the recruitment of neutrophils and promotion in macrophage phagocytosis. Nevertheless, the negative liquor of Rhizoma smilacis glabrae (PSORI-CM02 without RSG) also had anti-inflammatory and promoting macrophage phagocytosis effects. The results revealed the formula excluding RSG also had anti-inflammatory and immunoregulation effects, which demonstrated that RSG was not the major anti-inflammatory herbal medicine in PSORI-CM02. Similarly, astilbin was not the major anti-inflammatory active ingredient in the formula. The anti-inflammatory and the promotion of macrophage phagocytosis effect of PSORI-CM02 in vivo zebrafish were the results of multiple component interaction, which was the common characteristic of the Chinese medicine compound.

ASTILBIN: A PROMISING UNEXPLORED COMPOUND WITH MULTIDIMENSIONAL MEDICINAL AND HEALTH BENEFITS

BACKGROUND

Many flavonoids have various beneficial actions like anti-inflammatory, anti-carcinogenic properties and many other clinical conditions. Astilbin is one such flavanoid compound having many physiological as well as pharmacological actions.

PURPOSE

To summarize the important findings from the research conducted using astilbin having significance to its physiological and pharmacological activities as well as the patents filed using astilbin.

STUDY DESIGN

Systematic review and compilation of the collected literature.

METHOD

An extensive investigation of literature was done using several worldwide electronic scientific databases like PUBMED, SCOPUS, Science Direct and Google Scholar etc. All the article available in the English language that used our compound of interest i.e. astilbin, on the basis of inclusion criteria decided were retrieved from these databases, thoroughly reviewed and were summarized.

RESULT

It has been established that astilbin can play a vital in the management of diseases associated with immune system. It also possesses antibacterial, anti-oxidative and hepatoprotective activity.

CONCLUSION

These researches provide evidence that astilbin possesses great potential and thus can be utilized in the management of various disorders, thus establishing itself as a potential candidate for novel drug development. Also, there is still room for research on astilbin like it can be evaluated for anticancer potential, protective effect in various diabetic complications and many more. Overall observations from data suggested that astilbin is a promising compound and proved its efficacy in every preclinical study which is conducted till date. Some of the pharmacological activity is still unexplored. After successful preclinical trials, astilbin can go for further clinical trials.

Pharmacokinetic, bioavailability and tissue distribution study of astilbin in rats

OBJECTIVE

The purpose of this study is to reveal the pharmacokinetic profiles of astilbin with various doses in rats and investigate the oral absolute bioavailability and tissue distribution of astilbin after oral administration.

METHODS

Wistar rats were orally administered astilbin 12, 24 mg/kg and intravenous administered astilbin 6 mg/kg randomly. The concentration of astilbin in rat plasma and various tissue samples was determined by LC-MS/MS method. Noncompartmental pharmacokinetic parameters including AUC and t_1/2 were calculated from plasma concentration-time data of astilbin with the DAS 3.0.

KEY FINDINGS

After oral administration of astilbin 12 and 24 mg/kg to rats, the oral absolute bioavailability of astilbin were 1.16 ± 0.695% and 1.27 ± 0.379%; the plasma elimination half-lives (t_1/2 ) were 101 ± 35.8 and 109 ± 25.3 min, respectively. Astilbin had a rapid absorption and a wide distribution throughout the whole body except liver and fat following oral administration. Astilbin could penetrate the blood-brain barrier of rat.

CONCLUSIONS

The oral absolute bioavailability of astilbin is poor because of the low permeability and solubility. Both oral absorption and clearance of astilbin in rats are rapid after oral administration.

Astilbin promotes the induction of regulatory NK1.1- CD4+ NKG2D+ T cells through the PI3K, STAT3, and MAPK signaling pathways

Astilbin is a potential agent for autoimmune and inflammatory diseases and has a protective effect in mice with DSS-induced colitis. NK1.1- CD4+ NKG2D+ T cells are a subpopulation of regulatory T cells that produce TGF-β1 and IL-10. Whether astilbin directly promotes the induction of NK1.1- CD4+ NKG2D+ T cells and whether these astilbin-stimulated T cells exert an immune-regulatory role remain unclear. Here, we show that astilbin efficiently induces the production of NK1.1- CD4+ NKG2D+ T cells with high expressions of TGF-β1, IL-10, CCR6, and CCR9 in a dose-dependent manner ex vivo. These regulatory T cells also substantially inhibit the activities of CD8+ T cells and macrophages. Intraperitoneal injection of astilbin ameliorates the severity of colitis with an increase in the frequency of NK1.1- CD4+ NKG2D+ T cells in the colon tissue of DSS-treated mice. Moreover, adoptive transfer of NK1.1- CD4+ NKG2D+ T cells induced by astilbin remarkably protects against the onset of DSS-induced colitis. Finally, the PI3K, STAT3, and MAPK signaling pathways are involved in the induction of NK1.1- CD4+ NKG2D+ T cells by astilbin. Taken together, our study elucidates a new immune-regulatory mechanism of astilbin by inducing the regulatory NK1.1- CD4+ NKG2D+ T cells and indicates a potential clinical use of astilbin for patients with inflammatory bowel diseases.

H.pylori Infection Alleviates Acute and Chronic Colitis with the Expansion of Regulatory B Cells in Mice

Epidemiological studies showed that there was an inverse relationship between Helicobacter pylori (H. pylori) infection and the incidence of inflammatory bowel diseases (IBD). Our previous research indicated that the regulatory immune responses induced by H. pylori infection were not limited to gastric mucosa, and the balance of intestinal mucosal immunity was influenced. In this study, mice were infected with H. pylori SS1, and then colitis was induced by 3% dextran sulphate sodium (DSS), to investigate the role of the regulatory B cells in the effects of H. pylori infection on acute and chronic colitis. In acute and chronic colitis groups, DAI and colonic histological scores reduced significantly and colon length shorted less, the proinflammatory cytokines mRNA expression downregulated in colonic mucosa, and the percentages of CD19⁺IL-10⁺Breg cells were higher in the H. pylori/DSS co-treated groups compared with the DSS-treated groups. Our study suggests that H. pylori infection can alleviate the acute and chronic colitis induced by DSS, and CD19⁺IL-10⁺Breg cells may play a critical role in the alleviation of acute and chronic colitis following H. pylori infection.

Echinacoside alleviated LPS-induced cell apoptosis and inflammation in rat intestine epithelial cells by inhibiting the mTOR/STAT3 pathway

Inflammatory bowel disease (IBD) is a chronic and progressive inflammatory condition of colon and small intestine. Echinacoside (ECH) is a phenylethanoid glycoside that possesses various activities, including anti-inflammatory effect. However, the role of ECH in IBD is unknown. The present study aimed to evaluate the effect of ECH on LPS-induced rat intestine epithelial cells and the potential mechanisms. The results showed that LPS inhibited cell viability in time- and dose-dependent manners. ECH treatment attenuated the inhibition effect of LPS on cell viability. ECH alleviated LPS-induced apoptosis of rat intestine epithelial cells. ECH attenuated LPS-induced secretion and mRNA expression of TNF-α and IL-6, but enhanced LPS-induced secretion and mRNA expression of IL-10 and TGF-β1 in IEC-6 cells. The mTOR/STAT3 pathway was activated by LPS, while the activation was inhibited by ECH. Rapamycin, an inhibitor of mTOR, reversed the effect of LPS on rat intestine epithelial cells. In summary, this work suggested that ECH attenuated LPS-induced inflammation and apoptosis in rat intestine epithelial cells via suppressing the mTOR/STAT3 pathway. The findings indicated that ECH might be considered as a potential strategy for the treatment of IBD.

Astilbin emulsion improves guinea pig lesions in a psoriasis-like model by suppressing IL-6 and IL-22 via p38 MAPK

Astilbin has anti-inflammatory and immunoregulatory effects, and is frequently used in prescriptions treating psoriasis; however, the mechanism remains to be fully elucidated. In the present study, the effect of an astilbin microemulsion on a psoriasis‑like model in guinea pigs was examined, and the underlying mechanism was investigated. The levels of interkeukin (IL)‑6, IL‑17A and IL‑22 were determined using fluorescent reverse transcription‑quantitative polymerase chain reaction analysis and enzyme‑linked immunosorbent assays. The phosphorylation of p38 and extracellular signal‑regulated kinase (ERK)1/2 was detected using western blot analysis. Compared with the untreated control, astilbin significantly ameliorated the lesions induced by propranolol hydrochloride. The effect of astilbin on cytokine levels were cytokine‑ and drug‑concentration‑dependent. At a concentration of 2.22 µM, astilbin decreased the mRNA expression levels of IL‑6, IL‑17A and IL‑22 in lipopolysaccharide (LPS)‑induced HaCaT cells by 89, 69.1 and 69.3%, respectively. However, 2.22 µM astilbin had no effect on the protein expression of IL‑17A, and decreased the protein expression levels of IL‑6 and IL‑22 by 79.2 and 49.5%, respectively (P<0.05). At a concentration of 11.10 µM, astilbin decreased the mRNA expression of IL‑6, which was significantly induced by LPS, and significantly (P<0.05) decreased the protein expression levels of IL‑6 and IL‑22. Additionally, astilbin inhibited the LPS‑induced activation of phosphorylated p38. These results suggested that astilbin has the potential to be developed into a topical drug for the treatment of psoriasis via the inhibition of inflammatory cytokines.

Characterizing the binding interaction of astilbin with bovine serum albumin: a spectroscopic study in combination with molecular docking technology

Astilbin (ASN) is a flavonoid compound isolated from the rhizome of Smilax china L. (Smilacaceae). It has many bioactivities, such as selective immunosuppression, antioxidant, anti-hepatic injury, etc., and is widely used in traditional Chinese medical treatments. The interaction of ASN with bovine serum albumin (BSA) was studied in a physiological buffer (pH = 7.40) using multi-spectroscopic techniques in combination with molecular docking methods. UV-vis absorption measurements proved that a ASN–BSA complex could be formed. Fluorescence data revealed that ASN could strongly quench the intrinsic fluorescence of BSA in terms of a static quenching procedure. The process of binding was spontaneous and the binding occurred mainly through hydrogen bonding and van der Waals forces. The distance r between donor (BSA) and acceptor (ASN) was calculated to be 4.80 nm based on Förster's non-radiative energy transfer theory. The binding constant (K_a = 7.31 × 10⁴ mol L⁻¹) and the number of binding sites (n ≈ 1) at 298 K suggested that ASN only occupied one site in BSA with high affinity. Moreover, the results of molecular docking indicated that ASN was more likely to be located in site I (sub-domain IIA) of BSA. The results of synchronous fluorescence and three-dimensional fluorescence spectra showed that ASN induced conformational changes of BSA. The findings would be beneficial for research on the transportation, distribution and some important bioactivities of ASN in the human body.

The interaction of astilbin with bovine serum albumin was confirmed by multi-spectroscopic techniques and molecular docking methods.

Rutinosylated Ferulic Acid Attenuates Food Allergic Response and Colitis by Upregulating Regulatory T Cells in Mouse Models

The purpose of this study was to screen phytochemicals capable of inducing immune tolerance via enhanced transforming growth factor-β1 (TGF-β1) secretion and investigate their effects in a mouse model of food allergy and colitis. In a screening test using THP-1-derived dendritic cells, a significant increase in TGF-β1 levels was observed upon treatment with ferulic acid and its glycosides, among which ferulic acid rutinoside (FAR) induced the highest level of TGF-β1 secretion. Oral administration of FAR suppressed serum levels of immunoglobulin E and histamine in ovalbumin-sensitized mice and triggered the differentiation of regulatory T (Treg) cells. In comparison to the control, FAR treatment also induced stronger TGF-β1 secretion from splenic dendritic cells. FAR treatment attenuated dextran-sulfate-sodium-induced colitis in the model mice and induced Treg differentiation. These results suggest that FAR exerts potent immunomodulatory effects against allergic and intestinal inflammatory responses by inducing Treg differentiation.

The Effects of Astilbin on Cognitive Impairments in a Transgenic Mouse Model of Alzheimer's Disease

Bioflavonoids are being utilised as neuroprotectants in the treatment of various neurological disorders, including Alzheimer's disease (AD). Astilbin, a bioflavanoid, has been reported to have potent neuroprotective effects, but its preventive effects on amyloid-β (Aβ)-induced, Alzheimer's disease-related, cognitive impairment, and the underlying mechanisms of these effects have not been well characterised. Five-month-old APPswe/PS1dE9 transgenic mice were randomly assigned to a vehicle group and two astilbin (either 20 or 40 mg/kg per day, intraperitoneally) groups. After 8 weeks of treatment, we observed beneficial effects of astilbin (40 mg/kg per day), including lessening learning and memory deficits and reducing plaque burden and Aβ levels. Furthermore, the expressions of both the cAMP responsive element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) were significantly increased and the disturbance of AKT/GSK-3β signalling pathway was markedly ameliorated in the hippocampus of astilbin-treated (40 mg/kg per day) group. Our data suggest that astilbin might be a potential therapeutic agent against AD.

Astilbin ameliorates experimental autoimmune myasthenia gravis by decreased Th17 cytokines and up-regulated T regulatory cells

Astilbin, a major bioactive compound extracted from Rhizoma smilacis glabrae (RSG), has been reported to possess immunosuppressive properties. Our study first evaluated the effect of astilbin on experimental autoimmune myasthenia gravis (EAMG) in Lewis rats. The results showed that astilbin could attenuate the severity of EAMG by decreasing antigen-specific autoantibodies with up-regulation of regulatory T cells and down-regulation of Th17 cells. In addition to, astilbin also reduced the efficiency of the antigen presenting cells on which the expression of MHC class II decreased. These results suggest that astilbin might be a candidate drug for immunoregulation of EAMG, and provide us new treatment ideas for human myasthenia gravis (MG).

Lactobacillus curvatus WiKim38 isolated from kimchi induces IL-10 production in dendritic cells and alleviates DSS-induced colitis in mice

Probiotics such as lactobacilli and bifidobacteria have healthpromoting effects by immune modulation. In the present study, we examined the immunomodulatory properties of Lactobacillus curvatus WiKim38, which was newly isolated from baechu (Chinese cabbage) kimchi. The ability of L. curvatus WiKim38 to induce cytokine production in bone marrow-derived dendritic cells (BMDCs) was determined by enzyme-linked immunosorbent assay. To evaluate the molecular mechanisms underlying L. curvatus Wikim38-mediated IL-10 production, Western blot analyses and inhibitor assays were performed. Moreover, the in vivo anti-inflammatory effects of L. curvatus WiKim38 were examined in a dextran sodium sulfate (DSS)-induced colitis mouse model. L. curvatus WiKim38 induced significantly higher levels of IL-10 in BMDCs compared with that induced by LPS. NF-κB and ERK were activated by L. curvatus WiKim38, and an inhibitor assay revealed that these pathways were required for L. curvatus WiKim38-induced production of IL-10 in BMDCs. An in vivo experiment showed that oral administration of L. curvatus WiKim38 increased the survival rate of mice with DSS-induced colitis and improved clinical signs and histopathological severity in colon tissues. Taken together, these results indicate that L. curvatus Wikim38 may have health-promoting effects via immune modulation, and may thus be applicable for therapy of various inflammatory diseases.

Astilbin alleviates LPS-induced ARDS by suppressing MAPK signaling pathway and protecting pulmonary endothelial glycocalyx

Acute respiratory distress syndrome (ARDS) is a devastating disorder that is characterized by increased vascular endothelial permeability and inflammation. Unfortunately, no effective treatment beyond supportive care is available for ARDS. Astilbin, a flavonoid compound isolated from Rhizoma Smilacis Glabrae, has been used for anti-hepatic, anti-arthritic, and anti-renal injury treatments. This study examined the effects of Astilbin on pulmonary inflammatory activation and endothelial cell barrier dysfunction caused by Gram-negative bacterial endotoxin lipopolysaccharide (LPS). Endothelial cells from human umbilical veins or male Kunming mice were pretreated with Astilbin 24h before LPS stimulation. Results showed that Astilbin significantly attenuated the pulmonary histopathological changes and neutrophil infiltration 6h after the LPS challenge. Astilbin suppressed the activities of myeloperoxidase and malondialdehyde, as well as the expression of tumor necrosis factor-α and interleukin-6 in vivo and in vitro. As indices of pulmonary edema, lung wet-to-dry weight ratios, were markedly decreased by Astilbin pretreatment. Western blot analysis also showed that Astilbin inhibited LPS-induced activation of mitogen-activated protein kinase (MAPK) pathways in lung tissues. Furthermore, Astilbin significantly inhibited the activity of heparanase and reduced the production of heparan sulfate in the blood serum as determined by ELISA. These findings indicated that Astilbin can alleviate LPS-induced ARDS, which potentially contributed to the suppression of MAPK pathway activation and the degradation of endothelial glycocalyx.

A review of the efficacy of dietary polyphenols in experimental models of inflammatory bowel diseases

Crohn's disease and ulcerative colitis presently have no cure and are treated with anti-inflammatory drugs or monoclonal antibodies targeting pro-inflammatory cytokines. A variety of rodent models have been used to model chronic and acute colitis. Dietary polyphenols in foods and botanicals are of considerable interest for prevention and treatment of colitis. Many dietary polyphenols have been utilized for prevention of colitis in rodent models. Berries, green tea polyphenols, curcumin, and stilbenes have been the most extensively tested polyphenols in rodent models of colitis. The majority of polyphenols tested have inhibited colitis in rodents, but increasing doses of EGCG and green tea, isoflavones, flaxseed, and α-mangostin have exacerbated colitis. Few studies have examined combination of polyphenols or other bioactives for inhibition of colitis. Translating polyphenol doses used in rodent models of colitis to human equivalent doses reveals that supplemental doses are most likely required to inhibit colitis from a single polyphenol treatment. The ability to translate polyphenol treatments in rodent models is likely to be limited by species differences in xenobiotic metabolism and microbiota. Given these limitations, data from polyphenols in rodent models suggests merit for pursuing additional clinical studies for prevention of colitis.

Decrease of Functional Activated T and B Cells and Treatment of Glomerulonephitis in Lupus-Prone Mice Using a Natural Flavonoid Astilbin

Treatment of systemic lupus erythematosus (SLE), a chronic inflammatory disease, involves the long-term use of immunosuppressive agents with significant side effects. New therapeutic approaches are being explored to find better treatment possibilities. In this study, age-matched female MRL/lpr mice were treated orally with a natural flavonoid astilbin. Astilbin administration started either at week 8 or week 12 of age though week 20. In the early treatment regimen, the treatment with astilbin reduced splenomegaly / lymphomegaly, autoantibody production and ameliorated lupus nephitis. Several serum cytokines were significantly decreased upon treatment including IFN-g, IL-17A, IL-1b, TNF-a and IL-6. Both spleen CD44^hiCD62L^lo activated T cells and CD138⁺B220^- plasma cells greatly declined. Furthermore, astilbin treatment resulted in decreased mitochondrial membrane potential in activated T cells and downregulated expression of the co-stimulatory molecules CD80 and CD86 on LPS stimulated B cells. Similar but less profound effectiveness was observed in the mice with established disease in the late treatment regimen. These results indicate that the natural product astilbin can mitigate disease development in lupus-prone mice by decreasing functional activated T and B cells.

Optimization of astilbin extraction from the rhizome of Smilax glabra, and evaluation of its anti-inflammatory effect and probable underlying mechanism in lipopolysaccharide-induced RAW264.7 macrophages

Astilbin, a dihydroflavonol derivative found in many food and medicine plants, exhibited multiple pharmacological functions. In the present study, the ethanol extraction of astilbin from the rhizome of smilax glabra Roxb was optimized by response surface methodology (RSM) using Box-Behnken design. Results indicated that the obtained experimental data was well fitted to a second-order polynomial equation by using multiple regression analysis, and the optimal extraction conditions were identified as an extraction time of 40 min, ethanol concentration of 60%, temperature of 73.63 °C, and liquid-solid ratio of 29.89 mL/g for the highest predicted yield of astilbin (15.05 mg/g), which was confirmed through validation experiments. In addition, the anti-inflammatory efficiency of astilbin was evaluated in lipopolysaccharide (LPS)-induced RAW 264.7 cells. Results showed that astilbin, at non-cytotoxicity concentrations, significantly suppressed the production of nitric oxide (NO) and tumor necrosis factor-α (TNF-α), as well as the mRNA expression of inducible nitric oxide synthase (iNOS) and TNF-α in LPS-induced RAW 264.7 cells, but did not affect interleukin-6 (IL-6) release or its mRNA expression. These effects may be related to its up-regulation of the phosphorylation of p65, extracellular signal-regulated kinases 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK).

Effects of baicalin in CD4 + CD29 + T cell subsets of ulcerative colitis patients

AIM

To evaluate the role of baicalin in ulcerative colitis (UC) with regard to the CD4(+)CD29(+) T helper cell, its surface markers and serum inflammatory cytokines.

METHODS

Flow cytometry was used to detect the percentage of CD4(+)CD29(+) cells in patients with UC. Real time polymerase chain reaction was used to detect expression of GATA-3, forkhead box P3, T-box expressed in T cells (T-bet), and retinoic acid-related orphan nuclear hormone receptor C (RORC). Western blotting was used to analyze expression of nuclear factor-κB (NF-κB) p65, phosphorylation of NF-κB (p-NF-κB) p65, STAT4, p-STAT4, STAT6 and p-STAT6. The concentrations of interferon-γ (IFN-γ), interleukin (IL)-4, IL-5, IL-6, IL-10 and TGF-β in serum were determined by ELISA assay.

RESULTS

The percentages of CD4(+)CD29(+) T cells were lower in treatment with 40 and 20 μmol/L baicalin than in the treatment of no baicalin. Treatment with 40 or 20 μmol/L baicalin significantly upregulated expression of IL-4, TGF-β1 and IL-10, increased p-STAT6/STAT6 ratio, but downregulated expression of IFN-γ, IL-5, IL-6, RORC, Foxp3 and T-bet, and decreased ratios of T-bet/GATA-3, p-STAT4/STAT4 and p-NF-κB/NF-κB compared to the treatment of no baicalin.

CONCLUSION

The results indicate that baicalin regulates immune balance and relieves the ulcerative colitis-induced inflammation reaction by promoting proliferation of CD4(+)CD29(+) cells and modulating immunosuppressive pathways.