Periplocoside E, an Effective Compound from Periploca sepium Bge, Inhibited T Cell Activation in Vitro and in Vivo

Mechanistic insights into anti-inflammatory and immunosuppressive effects of plant secondary metabolites and their therapeutic potential for rheumatoid arthritis

The anti-inflammatory and immunosuppressive activities of plant secondary metabolites are due to their diverse mechanisms of action against multifarious molecular targets such as modulation of the complex immune system associated with rheumatoid arthritis (RA). This review discussed and critically analyzed the potent anti-inflammatory and immunosuppressive effects of several phytochemicals and their underlying mechanisms in association with RA in experimental studies, including preliminary clinical studies of some of them. A wide range of phytochemicals including phenols, flavonoids, chalcones, xanthones, terpenoids, alkaloids, and glycosides have shown significant immunosuppressive and anti-inflammatory activities in experimental RA models and a few have undergone clinical trials for their efficacy and safety in reducing RA symptoms and improve patient outcomes. These phytochemicals have potential as safer alternatives to the existing drugs in the management of RA, which possess a wide range of serious side effects. Sufficient preclinical studies on safety and efficacy of these phytochemicals must be performed prior to proper clinical studies. Further studies are needed to address the barriers that have so far limited their human use before the therapeutic potential of these plant-based chemicals as anti-arthritic agents in the treatment of RA is fully realized.

Simultaneous determination of periplocin, periplocymarin, periplogenin, periplocoside M and periplocoside N of Cortex Periplocae in rat plasma and its application to a pharmacokinetic study

A sensitive and specific ultra-performance liquid chromatographic-tandem mass spectrometric method was developed and validated to simultaneously determine periplocin, periplocymarin (PM), periplogenin (PG), periplocoside M (PSM) and periplocoside N (PSN) in rat plasma. Acetonitrile was employed to precipitate plasma with appropriate sensitivity and acceptable matrix effects. Chromatographic separation was performed using a Waters HSS T3 column with a gradient elution using water and acetonitrile both containing 0.1% formic acid and 0.1 mm ammonium formate within 8 min. Detection was performed in positive ionization mode using multiple reaction monitoring. The method was fully validated in terms of selectivity, linearity, accuracy, precision, recovery, matrix effects and stability. Using this method, the concentrations of periplocin, PM, PG, PSM and PSN were established after oral administration of Cortex Periplocae extract to rats, and the pharmacokinetic characteristics of periplocin, PM, PG, PSM and PSN were assessed. Generally, PM, PG, PSM and PSN were eliminated slowly and their half-lives were all >8 h. In addition, the systemic exposure of PSM showed significant differences between genders with more than 10 times higher area under the concentration-time curve in female rats than in male rats. The findings of this study provide useful information for further research on Cortex Periplocae.

Identification and mechanism of insecticidal periplocosides from the root bark of Periploca sepium Bunge

BACKGROUND

The Periploca sepium bark root (PSBR) has been regarded as a potential botanical insecticide because of its significant insecticidal activity of secondary metabolites. Several periplocosides were isolated from it as promising pesticides to control crop pests in agriculture.

RESULTS

In our research, two new periplocosides, along with four known periplocosides were isolated from PSBR. The names of new periplocosides were periplocoside T (PST) and periplocoside U (PSU) while another four periplocosides were known as follows: periplocoside A (PSA), periplocoside F (PSF), periplocoside E (PSE) and periplocoside D (PSD). All periplocosides were evalulated for insecticidal activity against 3rd Mythimna separata (Walker) and Plutella xylostella. The biometric data showed that periplocoside T, PSD and PSF had remarkable insecticidal activity against tested insects. Its values of LD₅₀ were 1.31, 3.94 and 3.42 μg·lavare^-1 against 3rd M. separata respectively, while the activity of those compounds against 3rd P. xylostella were 5.45, 12.17 and 13.95 μg·lavare^-1 , respectively. It was apparent after further study of the mechanism of action against M. separata was conducted that PST possessed the most significant insecticidal activity. The results of enzymatic activity displayed that powerful activation of tryptase, especially weak alkaline tryptase might be a dominant factor causing death of M. separata in vivo.

CONCLUSION

We herein report isolation and the mechanisms of action of insecticidal periplocosides, which established the fundamental development of natural agents to prevent pest damage to crops. © 2020 Society of Chemical Industry.

Anti-nociceptive, anti-inflammatory and anti-arthritic activities of pregnane glycosides from the root bark of Periploca sepium Bunge

ETHNOPHARMACOLOGICAL RELEVANCE

Periploca sepium Bunge (P. sepium) is used in traditional Chinese medicine (TCM) for the treatment of autoimmune diseases, particularly rheumatoid arthritis. Periploca sepium periplosides (PePs), isolated from the root bark of P. sepium, characterized as the cardiac glycosides-free pregnane glycosides fraction, is expected to possess therapeutic potential on inflammatory arthritis.

AIM OF THE STUDY

The current study is designed to evaluate the anti-nociceptive, anti-inflammatory and anti-arthritic activities effects of the PePs.

MATERIALS AND METHODS

The anti-nociceptive activity of PePs was examined in the writhing test and hot-plate test in mice. The anti-inflammatory activity of PePs was determined by the 2, 4-dinitro-1-fluorobenzene (DNFB)-induced ear edema model and the carrageenan induced paw edema model in mice. The anti-arthritic activity of PePs was investigated by evaluating the joint inflammation and arthritis pathology in rat adjuvant induced arthritis (AIA) and murine collagen induced arthritis (CIA). Phytohaemagglutinin M (PHA-M) -elicited human peripheral blood mononuclear cells (PBMCs) were further applied to assess the suppressive activity of PePs on IFN-γ and IL-17 production.

RESULTS

PePs treatment markedly decreased the acetic acid-induced visceral nociceptive response and increased the hot-plate pain threshold. Further, oral administration of PePs exhibited anti-inflammatory activity by decreasing DNFB-induced ear edema in mice and carrageenan-induced paw edema in rats. Moreover, oral treatment of PePs ameliorated joint swelling and attenuated bone erosion in rodent arthritis, and the therapeutic benefits were partially attributed to the suppression of proinflammatory cytokines such IFN-γ and IL-17. Moreover, PePs suppressed the proliferation as well as IFN-γ and IL-17 secretion in PHA-M-elicited human PBMCs in a concentration dependent manner.

CONCLUSIONS

Taken together, our results justified the traditional use of Periploca sepium Bunge for the treatment of diseases associated with inflammation and pain.

A simple "turn-on" fluorescence sensor for salicylaldehyde skeleton based on switch of PET-AIE effect

The selective detection of salicylaldehyde skeleton is of great significance in phytochemistry and biological research but rarely reported. In this research, a simple and highly selective "turn-on" fluorescence sensor (CDB-Am) for salicylaldehyde skeleton was developed based on switch of photoinduced electron transfer (PET) and aggregation-induced emission (AIE). CDB-Am bearing amino-cyanodistyrene structure responded to salicylaldehyde in the range of 3.1 to 40 μM with a detection limit of 0.94 μM. The sensing process of formation of Schiff-base adduct CDB-SA was confirmed by ¹H NMR, MS, and FT-IR spectra, revealing that a recovered AIE property accounted for the turn-on fluorescence response of CDB-Am and the intramolecular hydrogen bonding played a crucial role in the disruption of PET process. This sensing ability was successfully applied for both fluorescence qualitative test of salicylaldehyde skeleton on TLC analysis and quantitative detection of salicylaldehyde skeleton with good accuracy in the root bark of Periploca sepium, suggesting the extensive applications in phytochemistry and traditional Chinese herbal medicine. Furthermore, CDB-Am exhibited the first excellent fluorescence imaging ability in detecting salicylaldehyde skeleton in a living system. This work supplied a new strategy of preparing a novel "turn-on" fluorescence probe for detecting salicylaldehyde skeleton in complex environments and living bodies.

Minor immunosuppressive spiroorthoester group-containing pregnane glycosides from the root barks of Periploca sepium

LC-MS guided chemical investigation of the periploside-rich extract of the root barks of Periploca sepium afforded six new minor pregnane glycosides, named periplosides A1-A6 (1-6). Their structures were characterized on the basis of extensive spectroscopic analysis. Compounds 1-6 were evaluated for their inhibitory activities against the proliferation of T and B lymphocytes in vitro, among them, compound 5 exhibited significant inhibitory activities and the most favorite selective index (SI) values against the proliferation of T lymphocyte (IC₅₀ = 0.30 μM, SI = 176) and B lymphocyte (IC₅₀ = 0.55 μM, SI = 97).

In Vitro Metabolic Profiling of Periplogenin in Rat Liver Microsomes and its Associated Enzyme-kinetic Evaluation

Background:

Periplogenin, an active ingredient in Cortex Periplocae, is widely noted for its multiple biological activities; however, the metabolism of this compound has been scarcely investigated. The present report proposed the in vitro metabolic profiling and reaction pathways of periplogenin in rat liver microsomes.

Method and Results:

The metabolites of periplogenin in rat liver microsomes were analyzed. Two main metabolites, namely 14-hydroxy-3-oxo-14β-carda-4, 20 (22)-dienolide and 5, 14-dihydroxy-3-oxo-5β, 14β-card-20(22)-enolide were identified by HPLC-MSn, 1H-NMR and 13C-NMR. HPLC method was established for the simultaneous determination of periplogenin and its related metabolites (M0, M1 and M2), which was performed on Waters ODS column with a methanol-water solution (53:47, v/v) as mobile phase and descurainoside as an internal standard at 220 nm. The linearity ranges of M0, M1 and M2 were 0.64-820.51, 0.68-864.86 and 0.64-824.74 μM respectively with the regression coefficient (R2) above 0.9995. The limits of quantitation for these metabolites (M0, M1 and M2) were 0.18, 0.22 and 0.15 μM respectively. The developed method was also accurate (with relative errors of -3.6% to 3.2%) and precise (with relative standard deviations below 7.9%). The recoveries of the three analytes were above 85.7% with stability in the range of -2.4% to 3.6%. The enzyme-kinetic parameters of periplogenin including Vmax (6.08 ± 0.19 nmol/mg protein/min), Km (288.62 ± 14.54 μM) and Clint (21 ± 1.0 μL/min/mg protein) were calculated using nonlinear regression analysis.

Conclusion:

These findings significantly highlighted the metabolic pathways of periplogenin and also provided some reference data for future pharmacokinetic and pharmacodynamic studies.

Mechanistic Paradigms of Natural Plant Metabolites as Remedial Candidates for Systemic Lupus Erythromatosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder involving a dysregulated immune response which ultimately leads to multiple organ failure. Several immunological and cellular checkpoints are available as drug targets. However, the available chemosynthetic drugs such as non-steroidal anti-inflammatory drugs and corticosteroids provide limited therapy with extreme toxicities. Moreover, the disease heterogeneity in SLE is very difficult to manage by a single drug component. Hence, it is imperative to utilize the holistic capabilities of natural plant products as immunomodulators and intracellular signaling regulators, thereby providing an auxiliary option of treatment. Additionally, the herbal drugs also serve as symptomatic relief providers, thereby serving as a prophylactic remedy in case of cerebrovascular, hepatic, nephropathological, hematological, cardiopulmonary, mucocutaneous and musculoskeletal manifestations of SLE. The present review attempts to showcase the current state of knowledge regarding the utility of plant-derived phyto-metabolites with their probable mechanistic roles in treating SLE, by means of targeting the signaling cascade, proinflammatory cytokine production and B-T cell co-stimulation. It is hoped that further preclinical and clinical studies will be embarked upon in order to understand the underlying therapeutic and mechanistic aspects of these medicinal herbs.

Characterization of chemical components of Periplocae Cortex and their metabolites in rats using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

Periplocae Cortex, named Xiang-Jia-Pi in China, has been widely used to treat autoimmune diseases, especially rheumatoid arthritis. However, the in vivo substances of Periplocae Cortex remain unknown yet. In this study, an ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was used for profiling the chemical components and related metabolites of Periplocae Cortex. A total of 98 constituents were identified or tentatively characterized in Periplocae Cortex: 42 C21 steroidal glycosides, 10 cardiac glycosides, 23 organic acids, 4 aldehydes, 7 triterpenes, and 12 other types. Among them, 18 components were unambiguously identified by comparison with reference standards. In addition, 176 related xenobiotics (34 prototypes and 142 metabolites) were screened out and characterized in rats' biosamples (plasma, urine, bile, and feces) after the oral administration of Periplocae Cortex. Moreover, the metabolic fate of periplocoside S-4a, a C21 steroidal glycoside, was proposed for the first time. In summary, phase II reactions (methylation, glucuronidation, and sulfation), phase I reactions (hydrolysis reactions, oxygenation, and reduction), and their combinations were the predominant metabolic reactions of Periplocae Cortex in rat. It is the first report to reveal the in vivo substances and metabolism feature of Periplocae Cortex. This study also provided meaningful information for further pharmacodynamics study of Periplocae Cortex, as well as its quality control research.

Herbal compounds for rheumatoid arthritis: Literatures review and cheminformatics prediction

Rheumatoid arthritis (RA) is a systemic disease characterized by autoimmunity, joint inflammation, and cartilage destruction, which affects 0.5-1% of the population. Many compounds from herbal medicines show the potentials to treat RA. On this basis, the compounds with good pharmacokinetic behaviors and drug-likeness properties will be further studied and developed. Therefore, the herbal compounds with anti-RA activities were reviewed in this paper, and the cheminformatics tools were used to predict their drug-likeness properties and pharmacokinetic parameters. A total of 90 herbal compounds were analyzed, which were reported to be effective on RA models through anti-inflammation, chondroprotection, immunoregulation, antiangiogenesis, and antioxidation. Most of the herbal compounds have good drug-likeness properties. Most of the compounds can be an alternative and valuable source for anti-RA drug discovery.

Genus Periploca (Apocynaceae): A Review of Its Classification, Phytochemistry, Biological Activities and Toxicology

The genus Periploca belongs to the family Apocynaceae, which is composed of approximately ten species of plants according to incomplete statistics. Most of these plants serve as folk medicines with a long history, especially Periploca sepium and Periploca forrestii. The botanical classifications, chemical constituents, biological activities and toxicities of the genus Periploca were summarized in the literature from 1897 to early 2019. Though the botanical classification of this genus is controversial, these species are well-known to be rich sources of diverse and complex natural products-above all, cardiac steroids and C₂₁ pregnane steroids with special structures and obvious pharmacological activities. The various crude extracts and 314 isolated metabolites from this genus have attracted much attention in intensive biological studies, indicating that they are equipped with cardiotonic, anti-inflammatory, immunosuppressive, antitumor, antimicrobial, antioxidant, insecticidal and other properties. It is noteworthy that some cardiac glycosides showed hepatotoxicity and cardiotoxicity at certain doses. Therefore, in view of the medical and agricultural value of the genus Periploca, in-depth investigations of the pharmacology in vivo, the mechanisms of biological actions, and the pharmacokinetics of the active ingredients should be carried out in the future. Moreover, in order to ensure the safety of clinical medication, the potential toxicities of cardiac glycosides or other compounds should also be paid attention. This systematic review provides an important reference base for applied research on pharmaceuticals and pesticides from this genus.

Absolute Configuration of Periplosides C and F and Isolation of Minor Spiro-orthoester Group-Containing Pregnane-type Steroidal Glycosides from Periploca sepium and Their T-Lymphocyte Proliferation Inhibitory Activities

Further phytochemical investigation of the root bark of Periploca sepium afforded nine new spiro-orthoester group-containing pregnane-type glycosides termed periplosides O-V and 3-O-formyl-periploside A. The structures of these glycosides along with the absolute configuration of the unique seven-membered formyl acetal-bridged spiro-orthoester function and the 4,6-dideoxy-3-O-methyl-Δ³-2-hexosulosyl moiety were elucidated on the basis of spectroscopic data interpretation and chemical transformation. The absolute configurations of the major compounds periplosides C and F were established by single-crystal X-ray diffraction analysis. The isolated compounds were evaluated for their inhibitory activities against the proliferation of T-lymphocytes. As a result, periploside C, the most abundant glycoside containing a spiro-orthoester moiety found in the plant, exhibited the most favorite selective index value (SI = 82.5). The length and constitution of the saccharide chain in the periplosides were found to influence the inhibitory activity and the SI value.

C21 steroidal glycosides and oligosaccharides from the root bark of Periploca sepium

Four new C₂₁ steroidal glycosides (1-4), named perisepiumosides FI (1-4) together with six known steroidal glycosides (5-10) and four oligosaccharides (11-14), were isolated from the root bark of Periploca sepium. Their structures were characterized on the basis of 1D and 2D-NMR spectroscopic data as well as HR-ESI-MS analysis. The evaluation of inhibition activity against human A-549 and HepG2 cell lines indicated that compounds 2, 8, 10 and 13 showed different levels of cytotoxic activities with IC₅₀ values ranging from 0.61 to 7.86μM.

A Review on Phytochemistry and Pharmacology of Cortex Periplocae

Cortex Periplocae, as a traditional Chinese herbal medicine, has been widely used for autoimmune diseases, especially rheumatoid arthritis. Due to its potential pharmaceutical values, more studies about the biological activities of Cortex Periplocae have been conducted recently. Meanwhile, the adverse reaction of Cortex Periplocae is not a negligible problem in clinic. In this article, we reviewed a series of articles and summarized the recent studies of Cortex Periplocae in the areas of phytochemistry and pharmacology. More than 100 constituents have been isolated and identified from Cortex Periplocae, including steroids, cardiac glycosides, terpenoids, and fatty acid compounds. The crude extracts of Cortex Periplocae and its active compounds exhibit various biological activities, such as cardiotonic effect, anticancer action, and anti-inflammatory effect. This paper aims to provide an overall review on the bioactive ingredients, pharmacological effect, and toxicity of this plant. Furthermore, this review suggests investigating and developing new clinical usages according to the above pharmacological effects.

Neurotoxin from Naja naja atra venom inhibits skin allograft rejection in rats

BACKGROUND

Recent studies reported that Naja naja atra venom (NNAV) regulated immune function and had a therapeutic effect on adjunctive arthritis and nephropathy. We hypothesized that NNAV and its active component, neurotoxin (NTX), might inhibit skin allograft rejection.

METHODS

Skin allografts were used to induce immune rejection in rats. In addition, mixed lymphocyte culture (MLC) was used to mimic immune rejection reaction in vitro. Both NNAV and NTX were orally given starting from 5days prior to skin allograft surgery.

RESULTS

The results showed that oral administration of NNAV or NTX prolonged the survival of skin allografts and inhibited inflammatory response. The production of Th1 cytokines (IFN-γ, IL-2) was also suppressed. NTX inhibited T-cell proliferation and CD4(+) T cell division induced by skin allografts. NTX also showed immunosuppressive activity in mixed lymphocyte culture. Atropine alone inhibited Con A-induced proliferation of T cells and potentiated NTX' s inhibitory effects on T cells, while pilocarpine only slightly enhanced Con A-induced T cell proliferation and partially reversed the inhibitory effect of NTX. On the other hand, neither nicotine nor mecamylamine had an influence on NTX's inhibitory effects on Con A-induced T cell proliferation in vitro. NTX inhibited T cell proliferation by arresting the cell cycle at the G0/G1 phase.

CONCLUSIONS

The present study revealed that NNAV and NTX suppressed skin allograft rejection by inhibiting T cell-mediated immune responses. These findings suggest both NNAV and NTX as potential immunosuppressants for preventing the immune response to skin allografts.

Total synthesis of periploside A, a unique pregnane hexasaccharide with potent immunosuppressive effects

Periploside A is a pregnane hexasaccharide identified from the Chinese medicinal plant Periploca sepium, which features a unique seven-membered formyl acetal bridged orthoester (FABO) motif and potent immunosuppressive activities. Here, we show the synthesis of this molecule in a total of 76 steps with the longest linear sequence of 29 steps and 9.2% overall yield. The FABO motif is constructed via a combination of Sinaÿ's and Crich's protocol for the formation of orthoester and acetal glycosides, respectively. The 2-deoxy-β-glycosidic linkages are assembled stereoselectively with judicious choice of the glycosylation methods. The epimer at the spiro-quaternary carbon in the FABO motif has also been elaborated in a stereo-controlled manner. This epimer, as well as the synthetic analogues bearing the FABO motif, retain largely the inhibitory activities of periploside A against the proliferation of T-lymphocyte, indicating the importance of the chemical connection of the FABO motif to their immunosuppressive activity.

Histopathological effects and immunolocalization of periplocoside NW from Periploca sepium Bunge on the midgut epithelium of Mythimna separata Walker larvae

Periplocoside NW (PSNW) with pregnane glycoside skeleton is a novel insecticidal compound isolated from the root bark of Periploca sepium Bunge. This compound has a potent stomach poisoning activity against several insect pests. In this study, we observed the intoxication symptoms, investigated the histopathological effects and carried out immuno-electron microscopic localization of PSNW on the midgut epithelium of oriental armyworm Mythimna separata Walker larvae for better understanding its action mechanism against insects. Ultrastructural observations showed that cell damages caused by PSNW in the midgut of M. separata larvae are related to the degeneration of brush border microvilli. The dissolution of cytoskeletal structures in the interior and on the surface of microvilli was responsible for the decrease in size and eventual disappearance of microvilli when bubbles of cytoplasmic substances protrude into the midgut lumen of M. separata, thus resulting in cell death. The immuno-electron microscopic localization research showed that gold particle appeared on the microvilli layer of the midgut of M. separate larvae firstly. The density of gold particle gradually added with the time, and finally microvilli layer was destructed severely. Meantime, the gold particles were also presented to the intracellular organelle membrane and the organelles also were destructed. Therefore, we proposed that this membrane system on insect midgut epithelium cells is the initial acting site of PSNW against insects.

Immunosuppressive activity of alpinetin on activation and cytokines secretion of murine T lymphocytes

Abstract Alpinetin, a flavonoid compound extracted from the seeds of Alpinia katsumadai Hayata, has been known to possess antibacterial, anti-inflammatory and other important therapeutic activities. In the current study, we investigated alpinetin for its immunosuppressive effect on activation and cytokines secretion of murine T lymphocytes. The data showed that alpinetin markedly suppressed ConA-induced murine splenocyte proliferation, Th1/Th2 cytokines production, CD4(+) T-cell populations and ratio of CD4(+)/CD8(+). This inspired us to further study the effects of alpinetin in vivo. The results showed that administration of alpinetin suppressed T-cell-mediated delayed-type hypersensitivity reaction in mice. In addition, we studied signal transduction pathways about T-cell activation on puried murine T lymphocytes by Western-blot assay. The data revealed that alpinetin could shock the activation of NF-κB, NFAT2 signal transduction pathways. These observations indicated that alpinetin have potential effects in downregulating the immune system and might be developed as a useful immunosuppressive agent in treating undesired immune responses.

Lack of Mutagenicity Potential of Periploca sepium Bge. in Bacterial Reverse Mutation (Ames) Test, Chromosomal Aberration and Micronucleus Test in Mice

OBJECTIVES

The root barks of Periploca sepium Bge. (P. sepium) has been used in traditional Chinese medicine for healing wounds and treating rheumatoid arthritis. However, toxicity in high-doses was often diagnosed by the presence of many glycosides. The potential mutagenicity of P. sepium was investigated both in vitro and in vivo.

METHODS

This was examined by the bacterial reverse mutation (Ames) test using Escherichia coli WP2uvrA and Salmonella typhimurium strains, such as TA98, TA100, TA1535, and TA1537. Chromosomal aberrations were investigated using Chinese hamster lung cells, and the micronucleus test using mice.

RESULTS

P. sepium did not induce mutagenicity in the bacterial test or chromosomal aberrations in Chinese hamster lung cells, although metabolic activation and micronucleated polychromatic erythrocytes were seen in the mice bone marrow cells.

CONCLUSIONS

Considering these results, it is suggested that P. sepium does not have mutagenic potential under the conditions examined in each study.

Structural revision of periplocosides and periperoxides, natural immunosuppressive agents from the genus Periploca

The structures of a series of peroxy function containing pregnane glycosides isolated from Periploca sepium and Periploca forrestii were revised to be orthoester group bearing ones using 2D NMR spectroscopic techniques, as well as chemical transformations and X-ray crystallographic diffraction analysis. The orthoester function appears to be an essential structural feature for immunosuppressive activity.

Anti-inflammatory function of Withangulatin A by targeted inhibiting COX-2 expression via MAPK and NF-kappaB pathways

Withangulatin A (WA), an active component isolated from Physalis angulata L., has been reported to possess anti-tumor and trypanocidal activities in model systems via multiple biochemical mechanisms. The aim of this study is to investigate its anti-inflammatory potential and the possible underlying mechanisms. In the current study, WA significantly suppressed mice T lymphocytes proliferation stimulated with LPS in a dose- and time-dependent manner and inhibited pro-inflammation cytokines (IL-2, IFN-gamma, and IL-6) dramatically. Moreover, WA targeted inhibited COX-2 expression mediated by MAPKs and NF-kappaB nuclear translocation pathways in mice T lymphocytes, and this result was further confirmed by the COX-1/2 luciferase reporter assay. Intriguingly, administration of WA inhibited the extent of mice ear swelling and decreased pro-inflammatory cytokines production in mice blood serum. Based on these evidences, WA influences the mice T lymphocytes function through targeted inhibiting COX-2 expression via MAPKs and NF-kappaB nuclear translocation signaling pathways, and this would make WA a strong candidate for further study as an anti-inflammatory agent.

Investigation of the immunosuppressive activity of Physalin H on T lymphocytes

Physalis angulata is an annual herb widely used in folk medicine. It is mainly used for treating rheumatoid arthritis (RA). Following bioactivity-guided isolation, a representative immunosuppressive compound, Physalin H was been identified from this herb medicine. The purpose of this work was to assess the immunosuppressive activity of Physalin H on T cells and to explore its potential mode of action. The results showed that Physalin H in a dose-dependent manner significantly inhibited the proliferation of T cells induced by concanavalin A (ConA) and by the mixed lymphocyte culture reaction (MLR). This inhibitive activity was mainly due to interfering DNA replication in G1 stages. In vivo experiments showed that, administration of Physalin H dose-dependently suppressed CD4(+) T cell mediated delayed-type hypersensitivity (DTH) reactions, and suppressed antigen-specific T-cell response in ovalbumin (OVA) immunized mice. Further study indicated that Physalin H could modulate Th1/Th2 cytokine balance and induce the production of immune regulation target Heme oxygenase (HO)-1 in T-cells in vitro. In this study, we demonstrated the immunosuppressive effect of Physalin H on T cells both in vitro and in vivo, and the immunosuppressive activity might be attributed to the suppression of T cell activation and proliferation, the modulation of Th1/Th2 cytokine balance and the induction of HO-1 in T cells.

In vitro efficacy and safety of poly-herbal formulations

Indigenous plants are used as a traditional source of raw materials for the manufacture of medicines. Modernizing the ancient art of herbal medicine bequeathed from generations entails addressing two interrelated issues i.e. efficacy, and safety prior to their acceptance and use worldwide. The present study was designed to investigate three of our veterinary poly-herbal formulations - Phytocee an antistressor; Zigbir(R) a hepatoprotectant; and Zist(R) as an immunomodulator in the pertinent in vitro cell assay models in order to validate their therapeutic potential. Cellular antioxidant potential of Phytocee was demonstrated against AAPH induced oxidative stress using HepG2 cells. Zigbir(R) was confirmed as a hepatoprotectant against tert-butylhydroperoxide induced cytotoxicity in HepG2 cells. Immunomodulatory activity of Zist(R) was established by its ability to inhibit the proliferation of mitogen stimulated murine splenocytes in vitro. On treatment with Zist(R), a trend of decline in IL-6, and IL-12 levels was observed following stimulation with Con A, and LPS respectively in murine splenocytes. Further, all the three poly-herbal formulations were subjected to Ames II assay for ensuring their safety profile. Results epitomize that all the three poly-herbal formulations were devoid of significant mutagenic effect in TA98, and TAMix strains of Salmonella typhimurium under our experimental conditions.

Oxazolone-induced delayed type hypersensitivity reaction in the adult yucatan pigs. A useful model for drug development and validation

The purpose of this study was to establish a model of delayed type hypersensitivity (DTH) reaction in the ear skin of large animals such as adult Yucatan pigs, which may aid in evaluating the efficacy of therapeutic modalities of newly developed anti-inflammatory drugs. The pigs were sensitized with oxazolone, re-challenged with the same irritant six days later, and dosed with either vehicle or with cyclosporine A (CsA) before and after challenge. CsA reduced the redness, inhibited the accumulation of ear fluid and inflammatory cells, as well as the release of the inflammatory mediators. Further, CsA inhibited the proliferation of T cells collected from the spleens or PBMCs of CsA-treated pigs when these cells were stimulated in vitro with PMA plus Ionomycin. These results indicate that pig skin can be used to evaluate modalities for the purpose of developing drugs that may be used to treat DTH in humans.

Periplocoside A prevents experimental autoimmune encephalomyelitis by suppressing IL-17 production and inhibits differentiation of Th17 cells

AIM

The aim of this study was to determine the therapeutic effect of Periplocoside A (PSA), a natural product isolated from the traditional Chinese herbal medicine Periploca sepium Bge, in MOG(35-55) (myelin oligodendrocyte glycoprotein 35-55)-induced experimental autoimmune encephalomyelitis (EAE).

METHODS

Female C57BL/6 mice immunized with MOG(35-55) were treated with (50 mg/kg or 25 mg/kg) or without PSA following immunization and continuously throughout the study. The degree of CNS inflammation was evaluated by H&E staining. Anti-MOG-specific recall responses were analyzed by [3H]-Thymidine incorporation, ELISA, and RT-PCR. The proportion of IL-17-producing T cells was measured by flow cytometry.

RESULTS

Oral administration of PSA significantly reduced the incidence and severity of EAE, which closely paralleled the inhibition of MOG(35-55)-specific IL-17 production. Importantly, PSA inhibited the transcription of IL-17 mRNA and RORgammat. Further studies examining intracellular staining and adoptive transfer EAE validated the direct suppressive effect of PSA on Th17 cells. In vitro studies also showed that PSA significantly inhibited the differentiation of Th17 cells from murine purified CD4+ T cells in a dose-dependent manner.

CONCLUSION

PSA ameliorated EAE by suppressing IL-17 production and inhibited the differentiation of Th17 cells in vitro. Our results provide new insight into the potential mechanisms underlying the immunosuppressive and anti-inflammatory effects of PSA.

Immunosuppressive pregnane glycosides from Periploca sepium and Periploca forrestii

Nine pregnane glycosides containing peroxy functions in their sugar moieties (1-5 and 11-14), five oligosaccharides (6-10), six pregnane glycosides (15-20), and five cardiac glycosides (21-25) were isolated from the root barks of Periploca sepium Bge. (Asclepiadaceae) and the roots of Periploca forrestii Schltr. (Asclepiadaceae), two traditional Chinese medicines used for the treatment of rheumatoid arthritis. Among them, 1-8 are hitherto unknown. Their structures were characterized on the basis of spectroscopic analyses. In pharmacological testing, compounds 1-5 and 11-14 were found to exhibit inhibitory activity against the proliferation of T lymphocyte in vitro with IC50 values ranging from 0.29microM to 1.97microM, while the other components showed no significant inhibitory activity.

Periplocoside A, a pregnane glycoside from Periploca sepium Bge, prevents concanavalin A-induced mice hepatitis through inhibiting NKT-derived inflammatory cytokine productions

Periploca sepium Bge, a traditional Chinese herb medicine, is widely used for treating rheumatoid arthritis in china. Periplocoside A (PSA), a pregnane glycoside, is a new nature product compound isolated from P. sepium Bge. We examined the protective effects of PSA, on concanavaline A (ConA)-induced hepatitis. Pretreatment with PSA dramatically ameliorated ConA-induced liver injury, which was characterized by reducing serum alanine transaminase (ALT), pathogenic cytokines of interleukin (IL)-4 and interferon (IFN)-gamma levels, impeding the liver necrosis, and thus elevating the survival rate. In vitro, PSA inhibited IL-4 and IFN-gamma productions of alpha-galactosylceramide (alpha-GalCer) or anti-CD3-activated Natural killer T (NKT) cells. Enzyme Linked Immunosorbent Assay (ELISA) and Reverse Transcription Polymerase Chain Reaction (RT-PCR) assays revealed PSA suppressed IL-4 transcription and IFN-gamma translation. In conclusion, PSA had significantly preventative effect on ConA-induced hepatitis, which was closely associated with inhibition of NKT-derived inflammatory cytokine productions. These findings suggested that PSA has the therapeutic potential for treatment of human autoimmune-related hepatitis.

Suppressive effect of a novel water-soluble artemisinin derivative SM905 on T cell activation and proliferation in vitro and in vivo

Artemisinin and its derivatives exhibit potent immunosuppressive activity. The aim of this study was to investigate the suppressive effects of SM905, a new water-soluble artemisinin derivative, on T lymphocytes both in vitro and in vivo, and explore its potential mode of action. The results showed that SM905 had a high inhibitory activity in Concanavalin A (ConA)-induced splenocyte proliferation and mixed lymphocyte reaction, and a relatively low cytotoxicity in vitro. In ovalbumin-immunized mice, oral administration of SM905 dose-dependently suppressed T cell proliferative response to ovalbumin, and inhibited anti-ovalbumin interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) production by T cells. Further studies showed that SM905 inhibited TCR (T cell receptor)/CD3 plus CD28-mediated primary T cell proliferation and cytokine production (IL-2 and IFN-gamma), and exerted an inhibitory action on the phosphorylation of mitogen-activated protein (MAP) kinases including extracellular signal-regulated kinase (ERK), p38 and Jun N-terminal kinase (JNK), and the activation of Ras. The results of this study provided experimental evidence that the new artemisinin derivative SM905 had immunosuppressive effects both in vitro and in vivo. SM905 suppressed T cell activation, which was associated with the inhibition of MAP kinases and Ras activation. Our results suggested a potential of SM905 to be developed as a new type agent for treating T cell-mediated immune disorder.

Investigation of the immunosuppressive activity of artemether on T-cell activation and proliferation

BACKGROUND AND PURPOSE

Artemisinin and its derivatives exhibit potent immunosuppressive activity. The purpose of the current study was to examine the immunosuppressive activity of artemether directly on T lymphocytes and to explore its potential mode of action.

EXPERIMENTAL APPROACH

In vitro, T-cell proliferation was measured using [(3)H]-thymidine incorporation assay in cells stimulated with ConA, alloantigen and anti-CD3 antibody. CFSE-labeled cell division and cell cycle distribution were monitored by flow cytometry. In vivo, the effects of artemether were evaluated in delayed-type hypersensitivity (DTH) and purified T-cell responses to ovalbumin in ovalbumin-immunized mice. The activation of extracellular signal-regulated kinase1/2 (ERK1/2) and Raf1 were assessed by Western blot analysis and the activation of Ras was tested in pull-down assays.

KEY RESULTS

We show that, in vitro, artemether suppressed ConA- or alloantigen-induced splenocyte proliferation, influenced production of the cytokines IL-2 and IFN-gamma and inhibited cell cycle progression through the G0/G1 transition. In vivo, administration of artemether attenuated CD4 T-cell-mediated DTH reaction, and suppressed antigen-specific T-cell response in immunized mice. Further experiments showed that, treatment with artemether impaired both antigen- and anti-CD3-induced phosphorylation of ERK. In primary T cells, artemether profoundly inhibited anti-CD3-induced phosphorylation of Raf1 and activation of Ras.

CONCLUSIONS AND IMPLICATIONS

This study provided experimental evidence of the immunosuppressive effects of artemether directly on T cells both in vitro and in vivo. Its immunosuppressive mechanism involved inhibition of the activation of the Ras-Raf1-ERK1/2 protein kinase cascade in T cells.

A ReversibleS-Adenosyl-l-Homocysteine Hydrolase Inhibitor Ameliorates Experimental Autoimmune Encephalomyelitis by Inhibiting T Cell Activation

The reversible S-adenosyl-l-homocysteine hydrolase inhibitor DZ2002 [methyl 4-(adenin-9-yl)-2-hydroxybutanoate] suppresses antigen-induced-specific immune responses, particularly type 1 helper T cell (Th1)-type responses. Experimental autoimmune encephalomyelitis (EAE) is thought to be a Th1 cell-mediated inflammatory demyelinating autoimmune disease model of human multiple sclerosis (MS). In this study, we examined the effects of DZ2002 on active EAE induced by myelin oligodendrocyte glycoprotein (MOG) 35-55 in female C57BL/6 mice. Administration of DZ2002 (50 mg/kg/day i.p.) significantly reduced the incidence and severity of EAE, which was associated with the inhibition of MOG35-55-specific T cell proliferation and Th1-type cytokine production. In vitro studies also demonstrated that DZ2002 inhibited anti-CD3/28-induced naive T cell activation concomitant with the down-regulation of cyclin-dependent kinase (CDK) 4, CDK6, cyclin D3, and the up-regulation or protection of the CDK inhibitor p27. These findings highlight the fact that DZ2002 likely prevents EAE by suppressing T cell activation and suggest its utility in the treatment of MS and other Th1-mediated inflammatory diseases.

Periplocoside E inhibits experimental allergic encephalomyelitis by suppressing interleukin 12-dependent CCR5 expression and interferon-gamma-dependent CXCR3 expression in T lymphocytes

Periplocoside E (PSE) was found to inhibit primary T-cell activation in our previous study. Now we examined the effect and mechanisms of PSE on the central nervous system (CNS) demyelination in experimental allergic encephalomyelitis (EAE). C57BL/6 mice immunized with myelin oligodendrocyte glyco-protein (MOG) were treated with PSE following immunization and continued throughout the study. The effect on the progression of EAE and other relevant parameters were assessed. PSE reduced the incidence and severity of EAE. Spinal cord histopathology analysis showed that the therapeutic effect of PSE was associated with reduced mononuclear cell infiltration and CNS inflammation. As reverse transcription-polymerase chain reaction analysis showed, PSE decreased the CD4(+), CD8(+), and CD11b(+) cell infiltration. T cells from lymph nodes of MOG-immunized mice expressed enhanced levels of CCR5 and CXCR3 mRNA compared with T cells from normal mice. However, CCR5 and CXCR3 expressions were suppressed in T cells from PSE-treated mice. In vitro study also showed PSE inhibited interferon (IFN)-gamma-dependent CXCR3 expression in T cells through suppressing T-cell receptor (TCR) ligation-induced IFN-gamma production, whereas it inhibited interleukin (IL)-12-dependent CCR5 expression through suppressing IL-12 reactivity in TCR-triggered T cells. As a result, the initial influx of T cells into CNS was inhibited in PSE-treated mice. The consequent activation of macrophages/microglia cells was inhibited in spinal cord from PSE-treated mice as determination of chemokine expressions (CCL2, CCL3, CCL4, CCL5, CXCL9, and CXCL10). Consistently, the secondary influx of CD4(+), CD8(+), and CD11b(+) cells was decreased in spinal cords from PSE-treated mice. These findings suggest the potential therapeutic effect of PSE on multiple sclerosis.

(5R)-5-Hydroxytriptolide (LLDT-8), a novel triptolide derivative, prevents experimental autoimmune encephalomyelitis via inhibiting T cell activation

A novel triptolide derivative (5R)-5-hydroxytriptolide (LLDT-8) has been shown to have potent immunosuppressive activities. Here LLDT-8 was evaluated in experimental autoimmune encephalomyelitis (EAE), the model of multiple sclerosis (MS). LLDT-8 reduced the incidence and severity of EAE, which was associated with the inhibition of the MOG 35-55 lymphocyte recall response, anti-MOG 35-55 T cell responses, interleukin (IL)-2 and interferon (IFN)-gamma production. In vitro, LLDT-8 inhibited primary T cells proliferation, division, IL-2 and IFN-gamma production stimulated with anti-CD3/28. These findings highlight the fact that LLDT-8 prevents EAE by suppressing T cell proliferation and activation, with a potential for treatment of MS.