Ki Chul Hwang

Generation of regulatory dendritic cells and CD4+Foxp3+ T cells by probiotics administration suppresses immune disorders.

The beneficial effects of probiotics have been described in many diseases, but the mechanism by which they modulate the immune system is poorly understood. In this study, we identified a mixture of probiotics that up-regulates CD4+Foxp3+ regulatory T cells (Tregs). Administration of the probiotics mixture induced both T-cell and B-cell hyporesponsiveness and down-regulated T helper (Th) 1, Th2, and Th17 cytokines without apoptosis induction. It also induced generation of CD4+Foxp3+ Tregs from the CD4+CD25− population and increased the suppressor activity of naturally occurring CD4+CD25+ Tregs. Conversion of T cells into Foxp3+ Tregs is directly mediated by regulatory dendritic cells (rDCs) that express high levels of IL-10, TGF-β, COX-2, and indoleamine 2,3-dioxygenase. Administration of probiotics had therapeutical effects in experimental inflammatory bowel disease, atopic dermatitis, and rheumatoid arthritis. The therapeutical effect of the probiotics is associated with enrichment of CD4+Foxp3+ Tregs in the inflamed regions. Collectively, the administration of probiotics that enhance the generation of rDCs and Tregs represents an applicable treatment of inflammatory immune disorders.

Modification of mesenchymal stem cells for cardiac regeneration

Importance of the field: Mesenchymal stem cells (MSCs) have the greatest potential for use in cell-based therapy of human heart diseases, especially in myocardial infarcts. The therapeutic potential of MSCs in myocardial repair is based on the ability of MSCs to directly differentiate into cardiac tissue and on the paracrine actions of factors released from MSCs. However, the major obstacle in the clinical application of MSC-based therapy is the poor viability of the transplanted cells due to harsh microenvironments like ischemia, inflammation and/or anoikis in the infarcted myocardium. Recently, various approaches have been implemented in an effort to improve the survival of implanted MSCs through ex vivo manipulation of MSCs. Areas covered in this review: Major obstacles in MSC-based therapy are discussed, along with recent advances for enhancing therapeutic potential of engrafted MSCs from the past decade. What the reader will gain: This review focuses primarily on ex vivo manipulation of MSCs before transplantation, which includes pretreatment, preconditioning and genetic modification of MSCs, and future directions. Take home message: Modification of MSCs before transplantation has developed into a promising option for enhancing the beneficial effects of MSC-based therapy for cardiac repair after myocardial infarction.

A distal cis-regulatory element, CNS-9, controls NFAT1 and IRF4-mediated IL-10 gene activation in T helper cells

IL-10 is a multifunctional cytokine that plays a critical role in maintaining the balance between immunity and tolerance. Previously, we identified proximal regulatory elements and alterations of chromatin structure in the IL-10 gene loci of Th1 and Th2 cells. We have now characterized a crucial cis-regulatory element, CNS-9, located 9kb upstream of the transcription start site in IL-10 gene loci. The CNS-9 region is highly conserved in vertebrate genomes, and contains clustered NFAT and IRF binding motifs. In vitro binding of NFAT1 and IRF4 to the CNS-9 region was observed by EMSA. Furthermore, Th2-preferential in vivo binding of NFAT1 and IRF4 to the CNS-9 region was observed by ChIP. Cyclosporine A treatment on wild type Th2 cells or Th2 cells derived from NFAT1 knockout (NFAT1(-/-)) mice showed significantly reduced trans-activity of CNS-9. The Th2 subset-specific enhancer activity of CNS-9 was upregulated synergistically by NFAT1 and its partner IRF4. Mutations in the binding sites for NFAT1 and IRF4 abrogated its enhancer activity of CNS-9. Collectively, our results establish crucial roles for enhancer element CNS-9, and NFAT1 and IRF4 that bind to it, for IL-10 expression in differential T helper subsets.

Cordyceps pruinosa extracts induce apoptosis of HeLa cells by a caspase dependent pathway.

AIM OF THE STUDYnCordyceps is a parasitic fungus and has long been used as a traditional Chinese medicine to treat illnesses, promote longevity, increase athletic power, and relieve exhaustion and cancer. In this study, we reveal the mechanisms underlying apoptosis induced by Cordyceps pruinosa butanol fraction (CPBF) in the human cervical adenocarcinoma cell line, HeLa.nnnMATERIALS AND METHODSnProliferation and apoptosis of cells were examined by MTT assay, DNA fragmentation, phosphatidyl serine distribution assay, Western blot analysis, and immunocytochemistry. To determine the association between CPBF related apoptosis and ROS, electron spin resonance (ESR) trapping experiments were used.nnnRESULTSnCPBF inhibited proliferation and induced apoptosis in HeLa cells in a dose-dependent manner using a MTT assay, DNA fragmentation, and a phosphatidyl serine distribution assay. Western blot analysis showed that apoptosis in HeLa cells was caspase-3- and -9-dependent. Proteolytic cleavage of PARP and the release of cytochrome c from the mitochondria into the cytosol were significantly increased and the Bcl-2/Bax protein ratio was decreased. Apoptosis induced by CPBF was not prevented by various antioxidants.nnnCONCLUSIONSnThese results indicate that apoptotic effects of CPBF on HeLa cells are mediated by mitochondria-dependent death-signaling pathway independent of reactive oxygen species, suggesting that CPBF might be effective as an anti-proliferative agent for cancer.

Diabetes mellitus mitigates cardioprotective effects of remifentanil preconditioning in ischemia-reperfused rat heart in association with anti-apoptotic pathways of survival

Diabetes mellitus has been known to mitigate ischemic or pharmacologic preconditioning in ischemia-reperfusion injuries. Remifentanil is a widely used opioid in cardiac anesthesia that possesses a cardioprotective effect against ischemia-reperfusion. We evaluated whether diabetes affected remifentanil preconditioning induced cardioprotection in ischemia-reperfusion rat hearts in view of anti-apoptotic pathways of survival and Ca(2+) homeostasis. Streptozotocin-induced, diabetic rats and age-matched wild-type Sprague-Dawley rats were subjected to a left anterior descending coronary artery occlusion for 30min followed by 1h of reperfusion. Each diabetic and wild-type rat was randomly assigned to the sham, ischemia-reperfusion only, or remifentanil preconditioning group. Myocardial infarct size, activities of ERK1/2, Bcl2, Bax and cytochrome c, and gene expression influencing Ca(2+) homeostasis were assessed. Remifentanil preconditioning significantly reduced myocardial infarct size compared to ischemia-reperfusion only in wild-type rats but not in diabetic rats. Remifentanil preconditioning increased expression of ERK1/2 and anti-apoptotic protein Bcl-2 and decreased expression of pro-apoptotic proteins, Bax and cytochrome c, compared to ischemia-reperfusion only in wild-type rats. In diabetic rat hearts, however, remifentanil preconditioning failed to recover the phosphorylation state of ERK1/2 and to repress apoptotic signaling. In addition, diabetes minimized remifentanil induced modulation of abnormal changes in sarcoplasmic reticulum genes and proteins in ischemia-reperfusion rat hearts. In conclusion, diabetes mitigated remifentanil induced cardioprotection against ischemia-reperfusion, which might be associated with reduced recovery of the activities of proteins involved in anti-apoptotic pathways including ERK1/2 and the abnormal expression of sarcoplasmic reticulum genes as a result of ischemia-reperfusion in rat hearts.

Chemicals that modulate stem cell differentiation

Important cellular processes such as cell fate are likely to be controlled by an elaborate orchestration of multiple signaling pathways, many of which are still not well understood or known. Because protein kinases, the members of a large family of proteins involved in modulating many known signaling pathways, are likely to play important roles in balancing multiple signals to modulate cell fate, we focused our initial search for chemical reagents that regulate stem cell fate among known inhibitors of protein kinases. We have screened 41 characterized inhibitors of six major protein kinase subfamilies to alter the orchestration of multiple signaling pathways involved in differentiation of stem cells. We found that some of them cause recognizable changes in the differentiation rates of two types of stem cells, rat mesenchymal stem cells (MSCs) and mouse embryonic stem cells (ESCs). Among many, we describe the two most effective derivatives of the same scaffold compound, isoquinolinesulfonamide, on the stem cell differentiation: rat MSCs to chondrocytes and mouse ESCs to dopaminergic neurons.

Prediction of Left Atrial Fibrosis With Speckle Tracking Echocardiography in Mitral Valve Disease: A Comparative Study With Histopathology

Background and Objectives Left atrial (LA) fibrosis is a main determinant of LA remodeling and development of atrial fibrillation. However, non-invasive prediction of LA fibrosis is challenging. We investigated whether preoperative LA strain as measured by speckle tracking echocardiography could predict the degree of LA fibrosis and LA reverse remodeling after mitral valve (MV) surgery. Subjects and Methods Speckle tracking echocardiography and LA volume measurements were performed in 50 patients one day before MV surgery. LA tissues were obtained during the surgery, and the degrees of their interstitial fibroses were measured. LA volume measurements were repeated within 30 days after surgery (n=50) and 1-year later (n=39). Results Left atrial global strain was significantly correlated with the degree of LA fibrosis (r=-0.55, p<0.001), and its correlation was independent of age, underlying rhythm, presence of rheumatic heart disease and type of predominant MV disease (B=-1.37, 95% confidence interval -2.32 - -0.41, p=0.006). The degree of LA fibrosis was significantly correlated with early (r=-0.337, p=0.017) and 1-year (r=-0.477, p=0.002) percent LA volume reduction after MV surgery, but LA global strain was not significant. Conclusion Left atrial strain as measured by speckle tracking echocardiography might be helpful for predicting the degree of LA fibrosis in patients with MV disease.

Antiarrhythmic Potential of Mesenchymal Stem Cell Is Modulated by Hypoxic Environment

OBJECTIVESnThe purpose of this study was to evaluate the antiarrhythmic potential of mesenchymal stem cells (MSC) under a different environment.nnnBACKGROUNDnLittle is known about how environmental status affects antiarrhythmic potential of MSCs.nnnMETHODSnTo investigate the effect of paracrine factors secreted from MSCs under different circumstances on arrhythmogenicity in rats with myocardial infarction, we injected paracrine media (PM) secreted under hypoxic, normoxic conditions (hypoxic PM and normoxic PM), and MSC into the border zone of infarcted myocardium in rats.nnnRESULTSnWe found that the injection of hypoxic PM, but not normoxic PM, markedly restored conduction velocities, suppressed focal activity, and prevented sudden arrhythmic deaths in rats. Underlying this electrophysiological alteration was a decrease in fibrosis, restoration of connexin 43, alleviation of Ca(2+) overload, and recovery of Ca(2+)-regulatory ion channels and proteins, all of which is supported by proteomic data showing that several paracrine factors including basic fibroblast growth factor, insulinlike growth factor 1, hepatocyte growth factor, and EF-hand domain-containing 2 are potential mediators. When compared with PM, MSC injection did not reduce or prevent arrhythmogenicity, suggesting that the antiarrhythmic or proarrhythmic potential of MSC is mainly dependent on paracrine factors.nnnCONCLUSIONSnA hypoxic or normoxic environment surrounding MSC affects the type and properties of the growth factors or cytokines, and these secreted molecules determine the characteristics of the electro-anatomical substrate of the surrounding myocardium.

Therapeutic effect of magnesium lithospermate B on neointimal formation after balloon-induced vascular injury

Vascular smooth muscle cell (VSMC) proliferation and migration in response to platelet-derived growth factor (PDGF) play an important role in the development of atherosclerosis and restenosis. Recent evidence indicates that PDGF increases intracellular levels of reactive oxygen species in VSMCs and that both PDGF-induced VSMC proliferation and migration are reactive oxygen species-dependent. Danshen is a representative oriental medicine used for the treatment of vascular disease. Previously, we reported that magnesium lithospermate B, an active component of Danshen, is a potent antioxidant. Thus we investigated the therapeutic potential of magnesium lithospermate B in neointimal formation after carotid artery injury in rats along with its effects on the PDGF signaling pathway for stimulating VSMC proliferation and migration in vitro. PDGF is dimeric glycoprotein composed of two A or two B chains. In this study, we used PDGF-BB, which is one of the isoforms of PDGF (i.e., PDGF-AA, PDGF-BB, and PDGF-AB). Our results demonstrated that magnesium lithospermate B directly scavenged reactive oxygen species in a xanthine/xanthine oxidase system and reduced PDGF-BB-induced intracellular reactive oxygen species generation in VSMCs. In a rat carotid artery balloon injury model, magnesium lithospermate B treatment (10 mg/kg/day, i.p) showed a significant effect on the prevention of neointimal formation compared with vehicle treatment. In cultured VSMCs, magnesium lithospermate B significantly attenuated PDGF-BB-induced cell proliferation and migration as measured by 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2-tetrazolium bromide (MTT) assay and transwell migration assays, respectively. Further, magnesium lithospermate B inhibited PDGF-BB-induced phosphorylation of phospatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathways by scavenging reactive oxygen species. Together, these data indicated that magnesium lithospermate B, a potent reactive oxygen species scavenger, prevented both injury-induced neointimal formation in vivo and PDGF-BB-induced VSMC proliferation and migration in vitro, suggesting that magnesium lithospermate B may be a promising agent to prevent atherosclerosis and restenosis following angioplasty.

Calreticulin inhibits the MEK1,2-ERK1,2 pathway in α1-adrenergic receptor/Gh-stimulated hypertrophy of neonatal rat cardiomyocytes

In cardiac myocytes, stimulation of alpha(1)-adrenoceptor (AR) leads to a hypertrophic phenotype. The G(h) protein (transglutaminase II, TGII) is tissue type transglutaminase and transmits the alpha(1B)-adrenoceptor signal with GTPase activity. Recently, it has been shown that the calreticulin (CRT) down-regulates both GTP binding and transglutaminase activities of TGII. To elucidate whether G(h) mediates norepinephrine-stimulated intracellular signal transductions leading to activation of extracellular signal-regulated kinases (ERKs) and neonatal rat cardiomyocyte hypertrophy, we examined the effects of G(h) on the activation of ERKs and inhibitory effects of CRT on alpha(1)-adrenoceptor/G(h) signaling. In neonatal rat cardiomyocytes, norepinephrine-induced ERKs activation was inhibited by an alpha(1)-adrenoceptor blocker (prazosin), but not by an beta-adrenoceptor blocker (propranolol). Overexpression of the G(h) protein stimulated norepinephrine-induced ERKs activation, which was inhibited by alpha-adrenoceptor blocker (prazosin). Co-overexpression of G(h) and CRT abolished norepinephrine-induced ERKs activation. Taken together, norepinephrine induces hypertrophy in neonatal rat cardiomyocytes through alpha(1)-AR stimulation and G(h) is partly involved in norepinephrine-induced MEK1,2/ERKs activation. Activation of G(h)-mediated MEK1,2/ERKs was completely inhibited by CRT.