Qihe Xu

Omic techniques in systems biology approaches to traditional Chinese medicine research: Present and future ,

Omic techniques have become key tools in the development of systems biology. As the holistic approaches underlying the practice of traditional Chinese medicine (TCM) and new tendencies in Western medicine towards personalised medicine require in-depth knowledge of mechanisms of action and active compounds, the use of omic techniques is crucial for understanding and interpretation of TCM development, especially in view of its expansion in Western countries. In this short review, omic applications in TCM research are reviewed which has allowed some speculation regarding future perspectives for these approaches in TCM modernisation and standardisation. Guidelines for good practice for the application of omics in TCM research are also proposed.

Unexpected transcriptional induction of monocyte chemoattractant protein 1 by proteasome inhibition: involvement of the c-Jun N-terminal kinase-activator protein 1 pathway.

Proteasome inhibitors, the well-known inhibitors of NF-κB, are recently considered therapeutic agents for inflammation. However, the anti-inflammatory properties of these agents have not been fully evaluated. In this report we describe a novel effect of proteasome inhibitors on the expression of monocyte chemoattractant protein 1 (MCP-1) in mesangial cells. We found that proteasome inhibitor MG132 dose-dependently induced expression of MCP-1 at the transcriptional level. The stimulatory effect was similarly observed with other proteasome inhibitors (proteasome inhibitor 1 and lactacystin) and in other cell types (NRK fibroblasts). The 5′-flanking region of the MCP-1 gene contains multiple AP-1 sites. To explore the mechanisms involved, we examined the effects of proteasome inhibition on the AP-1 pathway. Northern blot analysis showed that MG132 rapidly induced the expression of c-jun, but not c-fos. Immunoblot analysis showed that MG132 prevented degradation of c-Jun protein. Kinase assay revealed that c-Jun N-terminal kinase (JNK) was rapidly activated by MG132. Consistent with these results, a reporter assay showed that AP-1 activity was up-regulated after treatment with MG132. Curcumin, a pharmacological inhibitor of the JNK-AP-1 pathway, abrogated the induction of MCP-1 by MG132. Similarly, stable transfection with a dominant-negative mutant of c-Jun attenuated both MG132-induced activation of AP-1 and expression of MCP-1. The transcriptional activation by proteasome inhibitors was observed not only in MCP-1, but also in other AP-1-dependent genes, including stromelysin and mitogen-activated protein kinase phosphatase 1. These data revealed that proteasome inhibition triggered the expression of MCP-1 and other genes via the multistep induction of the JNK-c-Jun/AP-1 pathway.

In vitro anti-fibrotic activities of herbal compounds and herbs

BACKGROUND We recently developed high-throughput assays of inflammation-independent anti-fibrotic activities based on TGF-beta1-induced total collagen accumulation and nodule formation in normal rat kidney fibroblasts. METHODS These assays were applied to examine the anti-fibrotic activities of 21 compounds isolated from plants used in Chinese medicine and methanol extracts of 12 Chinese herbs. Lactate dehydrogenase release assay and cell detachment index were used to monitor cytotoxicity. Changes in fibrogenic molecular markers were observed by reverse transcriptase quantitative polymerase chain reaction and high-content imaging analysis of immunofluorescence. RESULTS Three flavonoids (quercetin, baicalein and baicalin) and two non-flavonoids (salvianolic acid B and emodin) demonstrated anti-fibrotic activities in both total collagen accumulation and nodule formation assays. The remaining 16 compounds had little anti-fibrotic effect or were cytotoxic. The anti-fibrotic compounds suppressed collagen I expression at both mRNA and protein levels and also variably suppressed alpha-smooth muscle actin expression and bromodeoxyuridine incorporation. Methanol extracts of Scutellaria baicalensis Georgi, Salvia miltiorrhiza Bunge and Rheum palmatum L., which are rich sources of baicalein, baicalin, salvianolic acid B and emodin, respectively, also showed in vitro anti-fibrotic activities. CONCLUSIONS Five herbal compounds and three herbal extracts have in vitro anti-fibrotic activities. These data warrant further studies on these anti-fibrotic entities and suggest it a promising strategy to discover new anti-fibrotic drugs by screening more plant materials.

Transcriptional Induction of Mitogen-activated Protein Kinase Phosphatase 1 by Retinoids SELECTIVE ROLES OF NUCLEAR RECEPTORS AND CONTRIBUTION TO THE ANTIAPOPTOTIC EFFECT

All-trans-retinoic acid (t-RA) inhibits hydrogen peroxide (H2O2)-induced apoptosis by inhibiting the c-Jun N-terminal kinase (JNK)-activator protein 1 (AP-1) pathway. In this report, we examined the involvement of mitogen-activated protein kinase phosphatase 1 (MKP-1) in suppression of JNK and the antiapoptotic effect of t-RA and the roles of nuclear receptors in the regulation of MKP-1 by t-RA. We found that not only t-RA, but also a selective agonist of retinoic acid receptor (RAR), a selective agonist of retinoid X receptor (RXR), and a pan-agonist of RAR and RXR all induced MKP-1 at the transcriptional level. Activation of RAR was required for all of these triggering effects, but activation of RXR was required only for the RXR agonist-induced MKP-1 expression. Among the three RAR subtypes, RARα and RARγ, but not RARβ, mediated the t-RA-induced MKP-1 expression. The antiapoptotic effect of t-RA on H2O2-induced apoptosis in several cell types was correlated with the inducibility of MKP-1 by t-RA. Inhibition of MKP-1 by vanadate enhanced JNK phosphorylation and attenuated the antiapoptotic effect of t-RA. Furthermore, overexpression of MKP-1 inhibited H2O2-induced JNK phosphorylation and apoptosis. To our knowledge, this is the first to demonstrate that 1) MKP-1 is inducible by retinoids at the transcriptional level, 2) RXR and individual RAR subtypes have different roles in this process, and 3) the induced MKP-1 plays a significant role in mediating both JNK inhibition and the antiapoptotic effect of t-RA in oxidative stress.

Traditional Chinese medicine research in the post-genomic era: Good practice, priorities, challenges and opportunities

BACKGROUND AND AIMS GP-TCM is the 1st EU-funded Coordination Action consortium dedicated to traditional Chinese medicine (TCM) research. This paper aims to summarise the objectives, structure and activities of the consortium and introduces the position of the consortium regarding good practice, priorities, challenges and opportunities in TCM research. Serving as the introductory paper for the GP-TCM Journal of Ethnopharmacology special issue, this paper describes the roadmap of this special issue and reports how the main outputs of the ten GP-TCM work packages are integrated, and have led to consortium-wide conclusions. MATERIALS AND METHODS Literature studies, opinion polls and discussions among consortium members and stakeholders. RESULTS By January 2012, through 3 years of team building, the GP-TCM consortium had grown into a large collaborative network involving ∼200 scientists from 24 countries and 107 institutions. Consortium members had worked closely to address good practice issues related to various aspects of Chinese herbal medicine (CHM) and acupuncture research, the focus of this Journal of Ethnopharmacology special issue, leading to state-of-the-art reports, guidelines and consensus on the application of omics technologies in TCM research. In addition, through an online survey open to GP-TCM members and non-members, we polled opinions on grand priorities, challenges and opportunities in TCM research. Based on the poll, although consortium members and non-members had diverse opinions on the major challenges in the field, both groups agreed that high-quality efficacy/effectiveness and mechanistic studies are grand priorities and that the TCM legacy in general and its management of chronic diseases in particular represent grand opportunities. Consortium members cast their votes of confidence in omics and systems biology approaches to TCM research and believed that quality and pharmacovigilance of TCM products are not only grand priorities, but also grand challenges. Non-members, however, gave priority to integrative medicine, concerned on the impact of regulation of TCM practitioners and emphasised intersectoral collaborations in funding TCM research, especially clinical trials. CONCLUSIONS The GP-TCM consortium made great efforts to address some fundamental issues in TCM research, including developing guidelines, as well as identifying priorities, challenges and opportunities. These consortium guidelines and consensus will need dissemination, validation and further development through continued interregional, interdisciplinary and intersectoral collaborations. To promote this, a new consortium, known as the GP-TCM Research Association, is being established to succeed the 3-year fixed term FP7 GP-TCM consortium and will be officially launched at the Final GP-TCM Congress in Leiden, the Netherlands, in April 2012.

Retinoids as a potential treatment for experimental puromycin‐induced nephrosis

Puromycin aminonucleoside (PAN)‐induced nephrosis is a model of human minimal change disease. In rats, PAN induces nephrotic‐range proteinuria, renal epithelial cell (podocyte) damage, infiltration of mononuclear leukocytes, and apoptosis of several renal cell types. Retinoic acid (RA) modulates a wide range of biological processes, such as inflammation and apoptosis. Since renal damage by PAN is characterized by inflammatory infiltration and epithelial cell death, the effect of treatment with all‐trans RA (tRA) was examined in the PAN nephrosis model and in the cultured differentiated podocyte. Treatment with tRA 4 days after PAN injection did not inhibit the proteinuria peak but reversed it significantly. However, treatment with tRA both before and 2 days after the injection of PAN protected the glomerular epithelial cells, diminishing the cellular edema and diffuseness of the foot process effacement. Preservation of the podocyte architecture correlated with the inhibition of proteinuria. The anti‐inflammatory effect of tRA was evidenced by the inhibition of PAN‐induced interstitial mononuclear cell infiltration and the decreased renal expression of two molecules involved in monocyte infiltration: fibronectin and monocyte chemoattractant protein‐1. TUNEL assays showed that tRA inhibited the PAN‐induced apoptosis of cultured differentiated mouse podocytes. We conclude that tRA treatment may prevent proteinuria by protecting the podocytes from injury and diminishing the interstitial mononuclear infiltrate in the model of PAN nephrosis. Retinoids are a potential new treatment for kidney diseases characterized by proteinuria and mononuclear cell infiltration.

Omics and its potential impact on R&D and regulation of complex herbal products

In traditional Chinese medicine (TCM), multicomponent and principally plant-derived drugs are used for disease prevention, symptom amelioration and treatment in a personalized manner. Because of their complex composition and consequent multiple targets and treatment objectives, the application of omics techniques and other integrative approaches seems inherently appropriate and even necessary for the demonstration of their potential preclinical and clinical safety and efficacy. This perspectives article provides proposals for the application of omics methods to the investigation of complex herbal products (CHP),(1) including Chinese herbal medicines (CHM), both in vitro and in vivo, for preclinical and clinical toxicity, pharmacokinetics, pharmacodynamics and efficacy tests. Ultimately, such approaches could aid regulatory scrutiny and potential acceptance, although currently there is no regulatory requirement of omics-based data in any submitted dossier to any regulatory agency, including for conventional drugs and CHP. However, it has been acknowledged that such studies are being increasingly performed, and almost surely will eventually be included into regulatory submission dossiers, possibly initially as supplementary materials. Specifically for CHM and CHP, omics can play a role both in determining product composition and its variability and in monitoring biological effects in carefully selected platforms. Predicting the future is difficult, but it seems possible that regulatory acceptance of omics techniques and a systems biology approach for the study of TCM, CHM and CHP will not be long delayed. It is expected that current studies and plans employing omics techniques and other integrative approaches will prove to be positive and informative.

The quest for modernisation of traditional Chinese medicine

Traditional Chinese medicine (TCM) is an integral part of mainstream medicine in China. Due to its worldwide use, potential impact on healthcare and opportunities for new drug development, TCM is also of great international interest. Recently, a new era for modernisation of TCM was launched with the successful completion of the Good Practice in Traditional Chinese Medicine Research in the Post-genomic Era (GP-TCM) project, the European Union’s Seventh Framework Programme (FP7) coordination action on TCM research. This 3.5-year project that involved inputs from over 200 scientists resulted in the production of 20 editorials and in-depth reviews on different aspects of TCM that were published in a special issue of Journal of Ethnopharmacology (2012; volume 140, issue 3). In this narrative review, we aim to summarise the findings of the FP7 GP-TCM project and highlight the relevance of TCM to modern medicine within a historical and international context. Advances in TCM research since the 1950s can be characterised into three phases: Phase I (1950s-1970s) was fundamental for developing TCM higher education, research and hospital networks in China; Phase II (1980s-2000s) was critical for developing legal, economic and scientific foundations and international networks for TCM; and Phase III (2011 onwards) is concentrating on consolidating the scientific basis and clinical practice of TCM through interdisciplinary, interregional and intersectoral collaborations. Taking into account the quality and safety requirements newly imposed by a globalised market, we especially highlight the scientific evidence behind TCM, update the most important milestones and pitfalls, and propose integrity, integration and innovation as key principles for further modernisation of TCM. These principles will serve as foundations for further research and development of TCM, and for its future integration into tomorrow’s medicine.

MAP kinase-dependent, NF-κB-independent regulation of inhibitor of apoptosis protein genes by TNF-α

The inhibitor of apoptosis protein (IAP) family of molecules regulates apoptotic processes triggered by various stimuli. However, the mechanisms involved in the regulation of the IAP genes are not fully understood. In this report, we examined roles of nuclear factor‐κB (NF‐κB) and mitogen‐activated protein (MAP) kinases in tumor necrosis factor‐α (TNF‐α)‐induced expression of IAP genes. In human endothelial cells, TNF‐α induced c‐IAP1 and c‐IAP2, but not XIAP and TIAP/Survivin, at the transcriptional level. Inactivation of NF‐κB by overexpression of a super‐repressor mutant of IκBα did not affect the induction of IAPs by TNF‐α. In contrast, extracellular signal‐regulated kinase, p38 MAP kinase, and c‐Jun N‐terminal kinase were activated after stimulation with TNF‐α, and inhibition of each kinase by PD098059, SB203580, curcumin, or SP600125 substantially attenuated the TNF‐α‐induced c‐IAP1 and c‐IAP2 expression. To examine whether the MAP kinases‐mediated induction of IAPs contributes to survival of TNF‐α‐exposed cells, cells were pretreated with MAP kinase inhibitors and stimulated with TNF‐α. Treatment with kinase inhibitors alone did not induce apoptosis but enhanced markedly TNF‐α‐triggered apoptosis. Furthermore, overexpression of either c‐IAP1 or c‐IAP2 diminished the apoptosis‐promoting effects of MAP kinase inhibitors. These data indicated that TNF‐α induced expression of c‐IAP1 and c‐IAP2 via MAP kinases, but not via NF‐κB, and that MAP kinases participated in the inhibition of apoptosis by induction of c‐IAPs in TNF‐α‐stimulated endothelial cells. J. Cell. Physiol. 210: 703–710, 2007.

Retinoic Acid Regulation of Mesangial Cell Apoptosis

Retinoic acid (RA) is recently used for the treatment of experimental glomerular diseases. However, mechanisms underlying its therapeutic effects are largely unknown. We recently reported that RA has the potential for protecting certain cells from particular injury. A typical example is its effect on oxidant-induced apoptosis of mesangial cells. Mesangial cells exposed to hydrogen peroxide undergo apoptosis through activation of the c-Jun N-terminal kinase activator protein 1 pathway. RA dramatically inhibits this process via suppression of c-fos/c-jun expression and inhibition of the c-Jun N-terminal kinase activation. The anti-apoptotic effect of RA is mediated by both nuclear receptor dependent and nuclear receptor independent mechanisms and is, at least in part, mediated by induction of mitogen-activated protein kinase phosphatase 1. In this review, we briefly summarize the current knowledge on molecular mechanisms involved in the anti-apoptotic effects of RA.