Clinical Characteristics of Macrolide-Refractory Mycoplasma pneumoniae Pneumonia in Korean Children: A Multicenter Retrospective Study

Mycoplasma pneumoniae is a major causative pathogen of community-acquired pneumonia in children, and the treatment of choice is macrolides. There is an increasing trend in reports of refractory clinical responses despite macrolide treatment due to the emergence of macrolide-resistant M. pneumoniae. Early discrimination of macrolide-refractory M. pneumoniae pneumonia (MrMP) from macrolide-sensitive M. pneumoniae pneumonia (MSMP) is vital; however, testing for macrolide susceptibility at the time of admission is not feasible. This study aimed to identify the characteristics of MrMP in Korean children, in comparison with those of MSMP. In this multicenter study, board-certified pediatric pulmonologists at 22 tertiary hospitals reviewed the medical records from 2010 to 2015 of 5294 children who were hospitalized with M. pneumoniae pneumonia and administered macrolides as the initial treatment. One-way analysis of variance and the Kruskal-Wallis test were used to compare differences between groups. Of 5294 patients (mean age, 5.6 years) included in this analysis, 240 (4.5%), 925 (17.5%), and 4129 (78.0%) had MrMP, macrolide-less effective M. pneumoniae pneumonia, and MSMP, respectively. Compared with the MSMP group, the MrMP group had a longer fever duration, overall (13.0 days) and after macrolide use (8.0 days). A higher proportion of MrMP patients had respiratory distress, pleural effusion, and lobar pneumonia. The mean aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and C-reactive protein levels were the highest in the MrMP group, along with higher incidences of extrapulmonary manifestations and atelectasis (during and post infection). Pre-existing conditions were present in 17.4% (n = 725/4159) of patients, with asthma being the most common (n = 334/4811, 6.9%). This study verified that MrMP patients show more severe initial radiographic findings and clinical courses than MSMP patients. MrMP should be promptly managed by agents other than macrolides.

Associations between surrounding residential greenness and intelligence quotient in 6-year-old children

BACKGROUND

Residential greenness has been reported to be positively associated with health benefits for children, including improved cognitive function. We investigated the association between the intelligence quotient (IQ) of 6-year-old children in Seoul, South Korea and surrounding greenness currently and during the mothers' pregnancy. We also analyzed whether these effects differed by the type of greenness, such as natural or built greenness.

METHODS

This study considered 189 mother-child dyads from the Environment and Development of Children Cohort study, who lived in Seoul during the prenatal period and when the child was 6 years old. We defined surrounding greenness using Landsat image data from Korean Arirang satellite images with buffers within 100 m - 2000 m of the radius of each participant's residential address. We separately analyzed two types of greenness, namely natural and built greenness. The children's IQ (total, verbal, and performance IQ) was measured using the Korean Educational Developmental Institute's Wechsler Intelligence Scale for Children.

RESULTS

Prenatal exposure to built greenness in 500 m and 1000 m buffers was associated with children's total IQ in a full model [difference in IQ (95% CI): 3.46(0.68, 6.24) and 3.42 (0.53, 6.31) per interquartile increase in proportion of greenness]. However, postnatal exposure to built greenness in all buffers was associated in children's total IQ. We found a stronger association between children's total IQ and built greenness rather than natural greenness.

CONCLUSIONS

We found that 6-year-old children tended to score higher on total IQ if they lived in greener neighborhoods. The results provide further evidence of the health benefits of greenness and provide support for urban planning and public health to build healthy urban cities for children and pregnant women.

Convergence of human pluripotent stem cell, organoid, and genome editing technologies

The last decade has seen many exciting technological breakthroughs that greatly expanded the toolboxes for biological and biomedical research, yet few have had more impact than induced pluripotent stem cells and modern-day genome editing. These technologies are providing unprecedented opportunities to improve physiological relevance of experimental models, further our understanding of developmental processes, and develop novel therapies. One of the research areas that benefit greatly from these technological advances is the three-dimensional human organoid culture systems that resemble human tissues morphologically and physiologically. Here we summarize the development of human pluripotent stem cells and their differentiation through organoid formation. We further discuss how genetic modifications, genome editing in particular, were applied to answer basic biological and biomedical questions using organoid cultures of both somatic and pluripotent stem cell origins. Finally, we discuss the potential challenges of applying human pluripotent stem cell and organoid technologies for safety and efficiency evaluation of emerging genome editing tools.

A comparison of hepato-cellular in vitro platforms to study CYP3A4 induction

In vitro studies of drug toxicity and drug-drug interactions are crucial for drug development efforts. Currently, the utilization of primary human hepatocytes (PHHs) is the de facto standard for this purpose, due to their functional xenobiotic response and drug metabolizing CYP450 enzyme metabolism. However, PHHs are scarce, expensive, require laborious maintenance, and exhibit lot-to-lot heterogeneity. Alternative human in vitro platforms include hepatic cell lines, which are easy to access and maintain, and induced pluripotent stem cell (iPSC) derived hepatocytes. In this study, we provide a direct comparison of drug induced CYP3A4 and PXR expression levels of PHHs, hepatic cell lines Huh7 and HepG2, and iPSC derived hepatocyte like cells. Confluently cultured Huh7s exhibited an improved CYP3A4 expression and were inducible by up to 4.9-fold, and hepatocytes differentiated from human iPSCs displayed a 3.3-fold CYP3A4 induction. In addition, an increase in PXR expression levels was observed in both hepatic cell lines and iPSC derived hepatocytes upon rifampicin treatment, whereas a reproducible increase in PXR expression was not achieved in PHHs. Our results indicate that both hepatoma originated cell lines and iPSCs may provide alternative sources to primary hepatocytes, providing reliable and reproducible results for CYP3A4/PXR metabolism, upon in vitro maturation. This study may serve as a guide for the selection of suitable and feasible in vitro platforms for drug-drug interaction and toxicology studies.

Annual and seasonal patterns in etiologies of pediatric community-acquired pneumonia due to respiratory viruses and Mycoplasma pneumoniae requiring hospitalization in South Korea

Background

Community–acquired pneumonia (CAP) is one of the leading worldwide causes of childhood morbidity and mortality. Its disease burden varies by age and etiology and is time dependent. We aimed to investigate the annual and seasonal patterns in etiologies of pediatric CAP requiring hospitalization.

Methods

We conducted a retrospective study in 30,994 children (aged 0–18 years) with CAP between 2010 and 2015 at 23 nationwide hospitals in South Korea. Mycoplasma pneumoniae (MP) pneumonia was clinically classified as macrolide-sensitive MP, macrolide-less effective MP (MLEP), and macrolide-refractory MP (MRMP) based on fever duration after initiation of macrolide treatment, regardless of the results of in vitro macrolide sensitivity tests.

Results

MP and respiratory syncytial virus (RSV) were the two most commonly identified pathogens of CAP. With the two epidemics of MP pneumonia (2011 and 2015), the rates of clinical MLEP and MRMP pneumonia showed increasing trends of 36.4% of the total MP pneumonia. In children < 2 years of age, RSV (34.0%) was the most common cause of CAP, followed by MP (9.4%); however, MP was the most common cause of CAP in children aged 2–18 years of age (45.3%). Systemic corticosteroid was most commonly administered for MP pneumonia. The rate of hospitalization in intensive care units was the highest for RSV pneumonia, and ventilator care was most commonly needed in cases of adenovirus pneumonia.

Conclusions

The present study provides fundamental data to establish public health policies to decrease the disease burden due to CAP and improve pediatric health.

A case of vitamin D hydroxylation-deficient rickets type 1A caused by 2 novel pathogenic variants in CYP27B1 gene

Vitamin D hydroxylation-deficient rickets type 1A (VDDR1A, OMIM 264700) is a rare autosomal recessive inherited disorder. Pathogenic variants in the CYP27B1 gene lead to loss of 1α-hydroxylase activity. We report the case of a 22-month-old toddler who presented with growth retardation and delayed development. The patient exhibited the typical laboratory findings of VDDR1A, including hypocalcemia (calcium: 5.2 mg/dL), elevated serum level of alkaline phosphatase (2,600 U/L), elevated serum level of intact-parathyroid hormone (238 pg/mL), low 1,25(OH)2D3 level (11.2 pg/mL), and normal 25(OH)D3 level (40.7 ng/mL). His height and weight were 76.5 cm and 9.5 kg, respectively (both &lt;3rd percentile). The Bayley Scales of Infant and Toddler Development II indicated significantly delayed development (mental development index &lt;50, psychomotor development index &lt;50). The patient was a compound heterozygous for two novel pathogenic variants in the CYP27B1 gene: c.57_69del (p.Glu20Profs*2) and c.171dupG (p.Leu58Alafs*275), inherited from his mother and father, respectively. The patient showed remarkable improvement after treatment with calcitriol and calcium carbonate.

Human-relevant preclinical in vitro models for studying hepatobiliary development and liver diseases using induced pluripotent stem cells

IMPACT STATEMENT

In this review, we address the potential of human-induced pluripotent stem cell-based hepatobiliary differentiation technology as a means to study human liver development and cell fate determination, and to model liver diseases in an effort to develop a new human-relevant preclinical platform for drug development.

Transient c-Src Suppression During Endodermal Commitment of Human Induced Pluripotent Stem Cells Results in Abnormal Profibrotic Cholangiocyte-Like Cells

Directed differentiation of human induced pluripotent stem cells (iPSCs) toward hepatobiliary lineages has been increasingly used as models of human liver development/diseases. As protein kinases are important components of signaling pathways regulating cell fate changes, we sought to define the key molecular mediators regulating human liver development using inhibitors targeting tyrosine kinases during hepatic differentiation of human iPSCs. A library of tyrosine kinase inhibitors was used for initial screening during the multistage differentiation of human iPSCs to hepatic lineage. Among the 80 kinase inhibitors tested, only Src inhibitors suppressed endoderm formation while none had significant effect on later stages of hepatic differentiation. Transient inhibition of c-Src during endodermal induction of human iPSCs reduced endodermal commitment and expression of endodermal markers, including SOX17 and FOXA2, in a dose-dependent manner. Interestingly, the transiently treated cells later developed into profibrogenic cholangiocyte-like cells expressing both cholangiocyte markers, such as CK7 and CK19, and fibrosis markers, including Collagen1 and smooth muscle actin. Further analysis of these cells revealed colocalized expression of collagen and yes-associated protein (YAP; a marker associated with bile duct proliferation/fibrosis) and an increased production of interleukin-6 and tumor necrosis factor-α. Moreover, treatment with verteporfin, a YAP inhibitor, significantly reduced expression of fibrosis markers. In summary, these results suggest that c-Src has a critical role in cell fate determination during endodermal commitment of human iPSCs, and its alteration in early liver development in human may lead to increased production of abnormal YAP expressing profibrogenic proinflammatory cholangiocytes, similar to those seen in livers of patients with biliary fibrosis. Stem Cells 2019;37:306-317.

Derivation of a disease-specific human induced pluripotent stem cell line from a biliary atresia patient

Biliary atresia (BA) is a common cause of pediatric end-stage liver disease. While its etiology is not yet clear, evidence has suggested that BA results from interactions between genetic susceptibility and environmental factors. Disease relevant human cellular models of BA will facilitate identification of both genetic and environmental factors that are important for disease prevention and treatment. Here we report the generation of a human induced pluripotent stem cell line from a BA patient using episomal vectors. Patient-specific BA iPSC lines provide valuable tools for disease mechanism study and drug development.

Determination of Functional Activity of Human iPSC-Derived Hepatocytes by Measurement of CYP Metabolism

The advent of induced pluripotent stem cell (iPSC) technology has enabled the modeling of an array of specific human disease phenotypes, aiding in the increasingly important and indispensable understanding of disease progression and pathogenesis. Pluripotent stem cell-derived hepatocytes present a new avenue for drug screening and personalized drug testing toward precision medicine. CYP450 microsomal enzymes play a critical role in drug metabolism. Hence, CYP activity measurement of iPSC-derived hepatocytes is a vital prerequisite, to ensure metabolic functionality before proceeding to drug testing. Herein, we describe the protocol for measurement of different CYP450 enzyme activities in human iPSC-derived hepatocytes.

Alcohol Increases Liver Progenitor Populations and Induces Disease Phenotypes in Human IPSC-Derived Mature Stage Hepatic Cells

Alcohol consumption has long been a global problem affecting human health, and has been found to influence both fetal and adult liver functions. However, how alcohol affects human liver development and liver progenitor cells remains largely unknown. Here, we used human induced pluripotent stem cells (iPSCs) as a model to examine the effects of alcohol, on multi-stage hepatic cells including hepatic progenitors, early and mature hepatocyte-like cells derived from human iPSCs. While alcohol has little effect on endoderm development from iPSCs, it reduces formation of hepatic progenitor cells during early hepatic specification. The proliferative activities of early and mature hepatocyte-like cells are significantly decreased after alcohol exposure. Importantly, at a mature stage of hepatocyte-like cells, alcohol treatment increases two liver progenitor subsets, causes oxidative mitochondrial injury and results in liver disease phenotypes (i.e., steatosis and hepatocellular carcinoma associated markers) in a dose dependent manner. Some of the phenotypes were significantly improved by antioxidant treatment. This report suggests that fetal alcohol exposure may impair generation of hepatic progenitors at early stage of hepatic specification and decrease proliferation of fetal hepatocytes; meanwhile alcohol injury in post-natal or mature stage human liver may contribute to disease phenotypes. This human iPSC model of alcohol-induced liver injury can be highly valuable for investigating alcoholic injury in the fetus as well as understanding the pathogenesis and ultimately developing effective treatment for alcoholic liver disease in adults.

Expression kinetics of hepatic progenitor markers in cellular models of human liver development recapitulating hepatocyte and biliary cell fate commitment

Due to the limitations of research using human embryos and the lack of a biological model of human liver development, the roles of the various markers associated with liver stem or progenitor cell potential in humans are largely speculative, and based on studies utilizing animal models and certain patient tissues. Human pluripotent stem cell-based in vitro multistage hepatic differentiation systems may serve as good surrogate models for mimicking normal human liver development, pathogenesis and injury/regeneration studies. Here, we describe the implications of various liver stem or progenitor cell markers and their bipotency (i.e. hepatocytic- and biliary-epithelial cell differentiation), based on the pluripotent stem cell-derived model of human liver development. Future studies using the human cellular model(s) of liver and biliary development will provide more human relevant biological and/or pathological roles of distinct markers expressed in heterogeneous liver stem/progenitor cell populations.

Current Management of Alcoholic Hepatitis and Future Therapies

Alcohol is one of the most common etiologies of liver disease, and alcoholic liver disease overall is the second most common indication for liver transplantation in the United States. It encompasses a spectrum of disease, including fatty liver disease, alcoholic hepatitis (AH), and alcoholic cirrhosis. AH can range from mild to severe disease, with severe disease being defined as: Discriminant Function (DF) ≥ 32, or Model for End-stage Liver Disease (MELD) ≥ 21, or presence of hepatic encephalopathy. Management of the mild disease consists mainly of abstinence and supportive care. Severe AH is associated with significant mortality. Currently, there is no ideal medical treatment for this condition. Besides alcohol cessation, corticosteroids have been used with conflicting results and are associated with an inherent risk of infection. Overall steroids have shown short term benefit when compared to placebo, but they have no obvious long term benefits. Pentoxifylline does not improve survival in patients with severe AH and is no longer recommended based on the results of the STOPAH (Steroid Or Pentoxifylline for Alcoholic Hepatitis) trial. Anti-tumor necrosis factor (TNF) agents are associated with increased risk of life threatening infections and death. Currently, early stage trials are underway, mainly targeting novel pathways based on disease pathogenesis, including modulation of innate immune system, inhibition of gut-liver axis and cell death pathways, and activation of transcription factor farnesyl X receptor (FXR). Future treatment may lie in human induced pluripotent stem cell (iPSC) technology, which is currently under investigation for the study of pathogenesis, drug discovery, and stem cell transplantation. Liver transplantation has been reported with good results in highly selected patients but is controversial due to limited organ supply.

Genome editing systems in novel therapies

Genome editing is the process in which DNA sequences at precise genomic locations are modified. In the past three decades, genome editing by homologous recombination has been successfully performed in mouse for generating genetic models. The low efficiency of this process in human cells, however, had prevented its clinical application until the recent advancements in designer endonuclease technologies. The significantly improved genome editing efficiencies aided by ZFN, TALEN, and CRISPR systems provide unprecedented opportunities not only for biomedical research, but also for developing novel therapies. Applications based on these genome editing tools to disrupt deleterious genes, correct genetic mutations, deliver functional transgenes more effectively or even modify the epigenetic landscape are being actively investigated for gene and cell therapy purposes. Encouraging results have been obtained in limited clinical trials in the past two years. While most of the applications are still in proof-of-principle or preclinical development stages, it is anticipated that the coming years will see increasing clinical success in novel therapies based on the modern genome editing technologies. It should be noted that critical issues still remain before the technologies can be translated into more reliable therapies. These key issues include off-target evaluation, establishing appropriate preclinical models and improving the currently low efficiency of homology-based precise gene replacement. In this review we discuss the preclinical and clinical studies aiming at translating the genome editing technologies as well as the issues that are important for more successful translation.

IFNL3 genotype is associated with differential induction of IFNL3 in primary human hepatocytes

BACKGROUND

Lambda interferons (IFNLs) have potent antiviral activity against HCV, and polymorphisms within the IFNL gene cluster near the IFNL3 gene strongly predict spontaneous- and treatment-related HCV infection outcomes. The mechanism(s) linking IFNL polymorphisms and HCV control is currently elusive.

METHODS

IFNL induction was studied in primary human hepatocytes (PHH) from 18 human donors, peripheral blood mononuclear cells (PBMCs) from 18 human donors, multiple cell lines and induced pluripotent stem cell-derived hepatocyte-like cells (iPSC-hepatocytes) from 7 human donors. After stimulation with intracellular RNA and infectious HCV, quantitative PCR (qPCR) primers and probes were designed to distinguish and quantify closely related IFNL messenger (m)RNAs from IFNL1, IFNL2 and IFNL3.

RESULTS

PHH demonstrated the most potent induction of IFNLs, although had lower pre-stimulation levels compared to PBMCs, monocytes and cell lines. PHH stimulation with cytoplasmic poly I:C induced >1,000-fold expression of IFNL1, IFNL2 and IFNL3. PHH from donors who were homozygous for the favourable IFNL3 allele (IFNL3-CC) had higher IFNL3 induction compared to PHH from IFNL3-TT donors (P=0.03). Baseline IFNL mRNA expression and induction was also tested in iPSC-hepatocytes: iPSC-hepatocytes had significantly higher baseline expression of IFNLs compared to PHH (P<0.0001), and IFNL3 induction was marginally different in iPSC-hepatocytes by IFNL genotype (P=0.07).

CONCLUSIONS

Hepatocytes express IFNLs when stimulated by a synthetic viral RNA that signals the cell through the cytoplasm. IFNL induction may be greater in persons with the favourable IFNL3 allele. These data provide insight into the strong linkage between IFNL3 genetics and control of HCV infection.

Efficient and allele-specific genome editing of disease loci in human iPSCs

Efficient and precise genome editing is crucial for realizing the full research and therapeutic potential of human induced pluripotent stem cells (iPSCs). Engineered nucleases including CRISPR/Cas9 and transcription activator like effector nucleases (TALENs) provide powerful tools for enhancing gene-targeting efficiency. In this study, we investigated the relative efficiencies of CRISPR/Cas9 and TALENs in human iPSC lines for inducing both homologous donor-based precise genome editing and nonhomologous end joining (NHEJ)-mediated gene disruption. Significantly higher frequencies of NHEJ-mediated insertions/deletions were detected at several endogenous loci using CRISPR/Cas9 than using TALENs, especially at nonexpressed targets in iPSCs. In contrast, comparable efficiencies of inducing homologous donor-based genome editing were observed at disease-associated loci in iPSCs. In addition, we investigated the specificity of guide RNAs used in the CRISPR/Cas9 system in targeting disease-associated point mutations in patient-specific iPSCs. Using myeloproliferative neoplasm patient-derived iPSCs that carry an acquired JAK2-V617F point mutation and α1-antitrypsin (AAT) deficiency patient-derived iPSCs that carry an inherited Z-AAT point mutation, we demonstrate that Cas9 can specifically target either the mutant or the wild-type allele with little disruption at the other allele differing by a single nucleotide. Overall, our results demonstrate the advantages of the CRISPR/Cas9 system in allele-specific genome targeting and in NHEJ-mediated gene disruption.

Roles of reactive oxygen species in the fate of stem cells

SIGNIFICANCE

Stem cells are characterized by the properties of self-renewal and the ability to differentiate into multiple cell types, and thus maintain tissue homeostasis. Reactive oxygen species (ROS) are a natural byproduct of aerobic metabolism and have roles in cell signaling. Regulation of ROS has a vital role in maintaining "stemness" and differentiation of the stem cells, as well as in progression of stem-cell-associated diseases.

RECENT ADVANCES

As of late, much research has been done on the adverse effects of ROS in stem cells. However, recently it has become apparent that in some cases redox status of the stem cell does have a role in maintaining its identity as such. Both pluripotent and multipotent stem cell types have been reported to possess enzymatic and nonenzymatic mechanisms for detoxification of ROS and to correct oxidative damage to the genome as well as the proteome.

CRITICAL ISSUES

Although context dependent and somewhat varied among different stem cell types, the correlation seems to exist between antioxidant defense level and stem cell fate change (i.e., proliferation, differentiation, and death). Changes in stem cell redox regulation may affect the pathogenesis of various human diseases.

FUTURE DIRECTIONS

Dissecting the defined roles of ROS in distinct stem cell types will greatly enhance their basic and translational applications. Here, we discuss the various roles of ROS in adult, embryonic, and induced pluripotent stem cells.

In Vitro Modeling of Alcohol-Induced Liver Injury Using Human-Induced Pluripotent Stem Cells

Alcohol consumption has long been associated with a majority of liver diseases and has been found to influence both fetal and adult liver functions. In spite of being one of the major causes of morbidity and mortality in the world, currently, there are no effective strategies that can prevent or treat alcoholic liver disease (ALD), due to a lack of human-relevant research models. Recent success in generation of functionally active mature hepatocyte-like cells from human-induced pluripotent cells (iPSCs) enables us to better understand the effects of alcohol on liver functions. Here, we describe the method and effect of alcohol exposure on multistage hepatic cell types derived from human iPSCs, in an attempt to recapitulate the early stages of liver tissue injury associated with ALD. We exposed different stages of iPSC-induced hepatic cells to ethanol at a pathophysiological concentration. In addition to stage-specific molecular markers, we measured several key cellular parameters of hepatocyte injury, including apoptosis, proliferation, and lipid accumulation.

Efficient drug screening and gene correction for treating liver disease using patient-specific stem cells

Patient-specific induced pluripotent stem cells (iPSCs) represent a potential source for developing novel drug and cell therapies. Although increasing numbers of disease-specific iPSCs have been generated, there has been limited progress in iPSC-based drug screening/discovery for liver diseases, and the low gene-targeting efficiency in human iPSCs warrants further improvement. Using iPSC lines from patients with alpha-1 antitrypsin (AAT) deficiency, for which there is currently no drug or gene therapy available, we established a platform to discover new drug candidates and correct disease-causing mutation with a high efficiency. A high-throughput format screening assay, based on our hepatic differentiation protocol, was implemented to facilitate automated quantification of cellular AAT accumulation using a 96-well immunofluorescence reader. To expedite the eventual application of lead compounds to patients, we conducted drug screening utilizing our established library of clinical compounds (the Johns Hopkins Drug Library) with extensive safety profiles. Through a blind large-scale drug screening, five clinical drugs were identified to reduce AAT accumulation in diverse patient iPSC-derived hepatocyte-like cells. In addition, using the recently developed transcription activator-like effector nuclease technology, we achieved high gene-targeting efficiency in AAT-deficiency patient iPSCs with 25%-33% of the clones demonstrating simultaneous targeting at both diseased alleles. The hepatocyte-like cells derived from the gene-corrected iPSCs were functional without the mutant AAT accumulation. This highly efficient and cost-effective targeting technology will broadly benefit both basic and translational applications.

CONCLUSIONS

Our results demonstrated the feasibility of effective large-scale drug screening using an iPSC-based disease model and highly robust gene targeting in human iPSCs, both of which are critical for translating the iPSC technology into novel therapies for untreatable diseases.

Pluripotent stem cell-based cancer therapy: promise and challenges

The development of induced pluripotent stem cell (iPSC) technology has generated enthusiasm about the therapeutic potential of these cells for treating a variety of diseases. However, the evidence that they actually will be clinically useful is limited. Here, we discuss the potential therapeutic applications of iPSCs for treating cancer and other diseases and highlight the current barriers restricting their use.

Abstract 995: Transient low doses of DNA demethylating agents exert durable antitumor effects on hematological and epithelial tumor cells

Reversal of gene promoter DNA hypermethylation and associated abnormal gene silencing is an attractive approach to cancer therapy. The DNA methylation inhibitors, decitabine (5-aza-2′-deoxycytidine) and azacitidine (5-azacytidine) are proving efficacious clinically for hematological neoplasms, especially at lower, less toxic, doses. Experimentally, high doses induce rapid DNA damage and cytotoxicity, but these may not explain the prolonged time to response often seen in patients. We now show that transient exposure of cultured and primary leukemic and epithelial tumor cells to decitabine or azacitidine at clinically-relevant nanomolar doses, without causing immediate cytotoxicity, produces a “memory” for anti-tumor responses, including potent inhibition of subpopulations of cancer, stem-like cells which often resist other therapies. These inhibitory effects are accompanied by sustained decreases in genome-wide promoter DNA methylation with associated gene re-expression, and anti-tumor changes in multiple key cellular regulatory pathways, such as cell cycle events mediated through FOXM1, cell invasion and motility, and granulocyte and breast cancer cell maturation. Notably, most of the key pathways altered by decitabine or azacitidine involve high priority targets for pharmacologic anti-cancer strategies, which provides molecular basis for possible combination therapies. Thus, low dose decitabine and azacitidine regimens may potentially have broad applicability for cancer management.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 995. doi:1538-7445.AM2012-995

Transient low doses of DNA-demethylating agents exert durable antitumor effects on hematological and epithelial tumor cells

Reversal of promoter DNA hypermethylation and associated gene silencing is an attractive cancer therapy approach. The DNA methylation inhibitors decitabine and azacitidine are efficacious for hematological neoplasms at lower, less toxic, doses. Experimentally, high doses induce rapid DNA damage and cytotoxicity, which do not explain the prolonged time to response observed in patients. We show that transient exposure of cultured and primary leukemic and epithelial tumor cells to clinically relevant nanomolar doses, without causing immediate cytotoxicity, produce an antitumor "memory" response, including inhibition of subpopulations of cancer stem-like cells. These effects are accompanied by sustained decreases in genomewide promoter DNA methylation, gene reexpression, and antitumor changes in key cellular regulatory pathways. Low-dose decitabine and azacitidine may have broad applicability for cancer management.

In vivo liver regeneration potential of human induced pluripotent stem cells from diverse origins

Human induced pluripotent stem cells (iPSCs) are a potential source of hepatocytes for liver transplantation to treat end-stage liver disease. In vitro differentiation of human iPSCs into hepatic cells has been achieved using a multistage differentiation protocol, but whether these cells are functional and capable of engrafting and regenerating diseased liver tissue is not clear. We show that human iPSC-derived hepatic cells at various differentiation stages can engraft the liver in a mouse transplantation model. Using the same differentiation and transplantation protocols, we also assessed the ability of human iPSCs derived from each of the three developmental germ layer tissues (that is, ectoderm, mesoderm, and endoderm) to regenerate mouse liver. These iPSC lines, with similar but distinct global DNA methylation patterns, differentiated into multistage hepatic cells with an efficiency similar to that of human embryonic stem cells. Human hepatic cells at various differentiation stages derived from iPSC lines of different origins successfully repopulated the liver tissue of mice with liver cirrhosis. They also secreted human-specific liver proteins into mouse blood at concentrations comparable to that of proteins secreted by human primary hepatocytes. Our results demonstrate the engraftment and liver regenerative capabilities of human iPSC-derived multistage hepatic cells in vivo and suggest that human iPSCs of distinct origins and regardless of their parental epigenetic memory can efficiently differentiate along the hepatic lineage.

Hematopoietic cells as sources for patient-specific iPSCs and disease modeling

In addition to being an attractive source for cell replacement therapy, human induced pluripotent stem cells (iPSCs) also have great potential for disease modeling and drug development. During the recent several years, cell reprogramming technologies have evolved to generate virus-free and integration-free human iPSCs from easily accessible sources such as patient skin fibroblasts and peripheral blood samples. Hematopoietic cells from umbilical cord blood banks and Epstein Barr virus (EBV) immortalized B lymphocyte repositories represent alternative sources for human genetic materials of diverse backgrounds. Ability to reprogram these banked blood cells to pluripotency and differentiate them into a variety of specialized and functional cell types provides valuable tools for studying underlying mechanisms of a broad range of diseases including rare inherited disorders. Here we describe the recent advances in generating disease specific human iPSCs from these different types of hematopoietic cells and their potential applications in disease modeling and regenerative medicine.

Liver engraftment potential of hepatic cells derived from patient-specific induced pluripotent stem cells

Human induced pluripotent stem cells (iPSCs) are potential renewable sources of hepatocytes for drug development and cell therapy. Differentiation of human iPSCs into different developmental stages of hepatic cells has been achieved and improved during the last several years. We have recently demonstrated the liver engraftment and regenerative capabilities of human iPSC-derived multistage hepatic cells in vivo. Here we describe the in vitro and in vivo activities of hepatic cells derived from patient specific iPSCs, including multiple lines established from either inherited or acquired liver diseases, and discuss basic and clinical applications of these cells for disease modeling, drug screening and discovery, gene therapy and cell replacement therapy.

Molecular imaging and stem cell research

During the last decade, there has been enormous progress in understanding both multipotent stem cells such as hematopoietic stem cells and pluripotent stem cells such as embryonic stem cells and induced pluripotent stem cells. However, it has been challenging to study developmental potentials of these stem cells because they reside in complex cellular environments and aspects of their distribution, migration, engraftment, survival, proliferation, and differentiation often could not be sufficiently elucidated based on limited snapshot images of location or environment or molecular markers. Therefore, reliable imaging methods to monitor or track the fate of the stem cells are highly desirable. Both short-term and more permanent monitoring of stem cells in cultures and in live organisms have benefited from recently developed imaging approaches that are designed to investigate cell behavior and function. Confocal and multiphoton microscopy, time-lapse imaging technology, and series of noninvasive imaging technologies enable us to investigate cell behavior in the context of a live organism. In turn, the knowledge gained has brought our understanding of stem cell biology to a new level. In this review, we discuss the application of current imaging modalities for research of hematopoietic stem cells and pluripotent stem cells and the challenges ahead.

Alpha-Type 1 Polarized Dendritic Cells Loaded with Apoptotic Allogeneic Breast Cancer Cells Can Induce Potent Cytotoxic T Lymphocytes against Breast Cancer

Purpose

Various tumor antigens can be loaded onto dendritic cells (DCs) to induce a potent cytotoxic T lymphocyte (CTL) response in DC-based immunotherapy against breast cancer. However, in the clinical setting, obtaining a sufficient number of autologous tumor cells as a source of tumor antigens is a laborious process. We therefore investigated the feasibility of immunotherapy using breast-cancer-specific CTLs generated in vitro by use of alpha-type 1 polarized DCs (α DC1s) loaded with ultraviolet B-irradiated cells of the breast cancer cell line MCF-7.

Materials and Methods

αDC1s were induced by loading allogeneic tumor antigen generated from the MCF-7 UVB-irradiated breast cancer cell line. Antigen-pulsed αDC1s were evaluated by morphological and functional assays, and the breast-cancer-specific CTL response was analyzed by cytotoxic assay.

Results

The αDC1s significantly increased the expression of several molecules related to DC maturation without differences according to whether the αDC1s were loaded with tumor antigens. The αDC1s showed a high production of interleukin-12 both during maturation and after subsequent stimulation with CD40L, which was not significantly affected by loading with tumor antigens. Breast-cancer-specific CTLs against autologous breast cancer cells were successfully induced by αDC1s loaded with apoptotic MCF-7 cells.

Conclusion

Autologous DCs loaded with an allogeneic breast cancer cell line can generate potent breast-cancer-specific CTL responses. This may be a practical method for cellular immunotherapy in patients with breast cancer.

Applications of patient-specific induced pluripotent stem cells; focused on disease modeling, drug screening and therapeutic potentials for liver disease

The recent advances in the induced pluripotent stem cell (iPSC) research have significantly changed our perspectives on regenerative medicine by providing researchers with a unique tool to derive disease-specific stem cells for study. In this review, we describe the human iPSC generation from developmentally diverse origins (i.e. endoderm-, mesoderm-, and ectoderm- tissue derived human iPSCs) and multistage hepatic differentiation protocols, and discuss both basic and clinical applications of these cells including disease modeling, drug toxicity screening/drug discovery, gene therapy and cell replacement therapy.

Generation of endoderm-derived human induced pluripotent stem cells from primary hepatocytes

Recent advances in induced pluripotent stem (iPS) cell research have significantly changed our perspective on regenerative medicine. Patient-specific iPS cells have been derived not only for disease modeling but also as sources for cell replacement therapy. However, there have been insufficient data to prove that iPS cells are functionally equivalent to human embryonic stem (hES) cells or are safer than hES cells. There are several important issues that need to be addressed, and foremost are the safety and efficacy of human iPS cells of different origins. Human iPS cells have been derived mostly from cells originating from mesoderm and in a few cases from ectoderm. So far, there has been no report of endoderm-derived human iPS cells, and this has prevented comprehensive comparative investigations of the quality of human iPS cells of different origins. Here we show for the first time reprogramming of human endoderm-derived cells (i.e., primary hepatocytes) to pluripotency. Hepatocyte-derived iPS cells appear indistinguishable from hES cells with respect to colony morphology, growth properties, expression of pluripotency-associated transcription factors and surface markers, and differentiation potential in embryoid body formation and teratoma assays. In addition, these cells are able to directly differentiate into definitive endoderm, hepatic progenitors, and mature hepatocytes.

CONCLUSION

The technology to develop endoderm-derived human iPS cell lines, together with other established cell lines, will provide a foundation for elucidating the mechanisms of cellular reprogramming and for studying the safety and efficacy of differentially originated human iPS cells for cell therapy. For the study of liver disease pathogenesis, this technology also provides a potentially more amenable system for generating liver disease-specific iPS cells.

Abstract LB-88: Transient exposure to low-dose decitabine and azacytidine reprograms cancer cells to produce a prolonged antitumor response

Reversing abnormal promoter DNA hypermethylation to induce expression of abnormally silenced genes is an attractive cancer therapeutic strategy. The DNA methylation inhibitors, decitabine (5-aza-2′-deoxycytidine) and azacytidine (5-azacytidine), have proven clinically effective against hematological neoplasms especially with use of low, minimally toxic, doses. While, experimentally, high doses of these drugs induce DNA damage and cytotoxicity, the prolonged time for patient responses does not suggest acute tumor cell lysis. We now separate, for these drugs, cytotoxic effects at high doses from cellular reprogramming effects at low nanomolar doses. These latter subsequently reduce tumorigenicity of human leukemia and solid tumor cells, and for leukemia cells, blunt long term self-renewal. We correlate these effects with sustained, genome wide, promoter DNA de-methylation and gene re-expression, and an anti-tumor reprogramming of multiple central cancer pathways which regulate cell cycle entry, mitosis, proliferation, apoptosis, and dependence upon anaerobic glycolysis. Thus, decitabine and azacytidine represent drugs that can, at low nanomolar doses, simultaneously reverse major cancer pathways each of which are the focus of intense drug targeting efforts. This suggests these drugs are broadly applicable to cancer management.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-88.

[Reference interval of serum thyroid hormones in healthy Korean adults]

OBJECTIVES

This study was conducted to determine the reference interval of serum thyroid hormones (TSH, FT3, FT4) in healthy Korean adults.

METHODS

Health examination data from 1,591 healthy Korean adults who visited an university hospital were analyzed. Patients with specific health conditions capable of altering laboratory results were excluded from the study. Serum thyroid hormones were measured using IMMULITE 2000 (DPC, USA, 2002). Subjects were 18-65 years old; 911 were male, and 690 were female.

RESULTS

The arithmetic means of TSH, FT3, and FT4 values for male subjects were 1.28+/-1.84 microIU/ml, 3.23+/-0.57 pg/ml, and 1.42+/-0.22 ng/dl, respectively. In female subjects, the arithmetic means of TSH, FT3, and FT4 values were 1.49+/-2.08 microIU/ml, 3.08+/-0.54 pg/ml, and 1.29 +/-0.24 ng/dl, respectively. The arithmetic mean FT4 value for males decreased with age (p<0.01). The arithmetic mean FT3 value for females increased with age (p<0.01). The arithmetic mean thyroid hormone values of all study subjects differed significantly based on season. The arithmetic mean of male FT4 decreased with increasing BMI (p<0.01). The arithmetic mean of female FT3 increased with increasing BMI (p<0.01). The reference intervals recommended by the IMMULITE 2000 manufacturer are 0.40-4.00 microIU/ml for TSH, 1.80-4.20 pg/ml for FT3, and 0.80-1.90 ng/dl for FT4 (same values for both genders).

CONCLUSIONS

There was a significant difference in the interval of thyroid hormones between males and females, but the reference interval of IMMULITE 2000 was not established by gender. There is a need to reestablish the reference interval for thyroid hormones in Korean healthy adults.

Fetal to adult stem cell transition: knocking Sox17 off

What controls the inherent differences between fetal and adult hematopoietic stem cells (HSCs)? In this issue of Cell, Kim et al. (2007) demonstrate in mice that the endodermal transcription factor Sox17 is required for the maintenance of fetal and neonatal but not adult HSCs.

A low level of reactive oxygen species selects for primitive hematopoietic stem cells that may reside in the low-oxygenic niche

A low-oxygenic niche in bone marrow limits reactive oxygen species (ROS) production, thus providing long-term protection for hematopoietic stem cells (HSCs) from ROS stress. Although many approaches have been used to enrich HSCs, none has been designed to isolate primitive HSCs located within the low-oxygenic niche due to difficulties of direct physical access. Here we show that an early HSC population that might reside in the niche can be functionally isolated by taking advantage of the relative intracellular ROS activity. Many attributes of primitive HSCs in the low-oxygenic osteoblastic niche, such as quiescence, and calcium receptor, N-cadherin, Notch1, and p21 are higher in the ROS(low) population. Intriguingly, the ROS(low) population has a higher self-renewal potential. In contrast, significant HSC exhaustion in the ROS(high) population was observed following serial transplantation, and expression of activated p38 mitogen-activated protein kinase (MAPK) and mammalian target of rapamycin (mTOR) was higher in this population. Importantly, treatment with an antioxidant, a p38 inhibitor, or rapamycin was able to restore HSC function in the ROS(high) population. Thus, more potent HSCs associated with the low-oxygenic niche can be isolated by selecting for the low level of ROS expression. The ROS-related signaling pathways together with specific characteristics of niche HSCs may serve as targets for beneficial therapies.

Stem cell plasticity: a rare cell, not a rare event

Purification to homogeneity for a rare stem cell (SC) population by both function and phenotype is a prerequisite to determine if SCs can change their fate (plasticity). Since cell fate determination has been suggested by both external environmental cues and intrinsic gene regulation, plasticity should be studied using both influences. Different frequencies of marrow SC plasticity may be attributed to either different isolation technologies or different developmental stage SCs with more or less multipotentiality. Tissue-specific SCs may reside in marrow, or alternatively, primitive marrow SC may respond directly to regenerative signals by migration to injury sites and repairing the damaged tissue. It is important to dissect the relationship between primitive/tissue-specific SCs and regenerative signals.

Metamorphosis from bone marrow derived primitive stem cells to functional liver cells

Both stem cell plasticity and cell fusion have been implicated as physiological responses to tissue injury. It remains the ultimate goal for the future to understand the regulatory control of each during regeneration. In our recent paper by Jang et al. we demonstrate the repair of damaged liver by bone marrow derived stem cells (SCs) in response to microenvironmental cues. Within 48 hrs after transplantation or co-culture, conversion of SCs into liver cells was observed. Fusion was ruled out as a major mechanism of this functional regeneration. Direct differentiation of SCs into liver epithelial cells may be clinically useful. However, if plasticity or fusion results in abnormal genetic changes they could be harmful. Before proceeding with therapeutic applications, the consequences of cellular therapy accompanying both plasticity and fusion must be examined in multiple animal models. Functional repair should also be demonstrated prior to treatment in patients.

Hematopoietic stem cells convert into liver cells within days without fusion

Both plasticity and cell fusion have been suggested to have a role in germ-layer switching. To understand the mechanisms underlying cell fate changes, we have examined a highly enriched population of hematopoietic stem cells (HSCs) in vitro or in vivo in response to injury for liver-specific phenotypic and functional changes. Here we show that HSCs become liver cells when cocultured with injured liver separated by a barrier. Chromosomal analyses and tissue-specific gene and/or protein expression show that microenvironmental cues rather than fusion are responsible for conversion in vitro. We transplanted HSCs into liver-injured mice and observed that HSCs convert into viable hepatocytes with increasing injury. Notably, liver function was restored 2-7 d after transplantation. We conclude that HSCs contribute to the regeneration of injured liver by converting into functional hepatocytes without fusion.

Protective effect of harmaline and harmalol against dopamine- and 6-hydroxydopamine-induced oxidative damage of brain mitochondria and synaptosomes, and viability loss of PC12 cells

The present study elucidated the protective effect of beta-carbolines (harmaline, harmalol and harmine) against oxidative damage of brain mitochondria, synaptosomes and PC12 cells induced by either dopamine or 6-hydroxydopamine. Harmaline, harmalol and antioxidant enzymes (superoxide dismutase/SOD and catalase) decreased the alteration of mitochondrial swelling and membrane potential induced by 200 microM dopamine or 100 microM 6-hydroxydopamine. Deprenyl attenuated the dopamine-induced mitochondrial dysfunction but did not reduce the effect of 6-hydroxydopamine. While beta-carbolines inhibited the electron flow in mitochondria, they did not enhance the depressant effect of catecholamines. beta-Carbolines and antioxidant enzymes reversed the depression of synaptosomal Ca2+ uptake induced by 10 microM catecholamines. The compounds inhibited the catecholamine-induced thioredoxin reductase inhibition, thiol oxidation and carbonyl formation in mitochondria and synaptosomes. beta-Carbolines decreased the reactive species-induced deoxyribose degradation. Harmaline and harmalol reduced the catecholamine-induced loss of the transmembrane potential and of cell viability in PC12 cells. beta-Carbolines alone did not show a significant cytotoxic effect on PC12 cells. The results suggest that beta-carbolines may attenuate the dopamine- or 6-hydroxydopamine-induced alteration of brain mitochondrial and synaptosomal functions, and viability loss in PC12 cells, by a scavenging action on reactive oxygen species and inhibition of thiol oxidation.

Effect of iron and ascorbate on cyclosporine-induced oxidative damage of kidney mitochondria and microsomes

The stimulatory effect of iron and ascorbate on the damaging action of cyclosporine in kidney mitochondria, microsomes and epithelial cells was examined. Cyclosporine induced malondialdehyde formation and hydrogen peroxide production in mitochondria and attenuated the activity of MnSOD and glutathione peroxidase. The damaging effect of cyclosporine (50 microM) plus Fe2+(20 microM) on mitochondrial and microsomal lipids and proteins as well as mitochondrial thiols was greater than the summation of the oxidizing action of cyclosporine alone and Fe2+ alone. As for tissue components, iron enhanced cyclosporine-induced viability loss in kidney epithelial cells. Fe2+, EDTA and H2O2- induced 2-alpha deoxyribose degradation was attenuated by 10 mM DMSO and 200 microM DTPA but not affected by 200 microM cyclosporine. The addition of Fe2+ caused a change in the absorbance spectrum of cyclosporine in the wavelength range 230-350 nm. The simultaneous addition of cyclosporine (50 microM) and ascorbate (100 microM) showed the enhanced peroxidative effect on mitochondrial and microsomal lipids, which was inhibited by DTPA and EDTA (1 mM). Similar to iron, ascorbate enhanced cyclosporine-induced cell viability loss. The results show that iron and ascorbate promote the damaging action of cyclosporine in kidney cortex mitochondria and microsomes and in kidney epithelial cells, which may contribute to the enhancement of cyclosporine-induced nephrotoxicity.

Differential regulation of protein tyrosine kinase on free radical production, granule enzyme release, and cytokine synthesis by activated murine peritoneal macrophages

The present study examined the regulatory effect of tyrosine kinase inhibitors (genistein, tyrphostin, and 2,5-dihydroxycinnamate) on the free radical production, granule enzyme release, and synthesis of interleukin (IL)-8 and granulocyte macrophage-colony stimulating factor (GM-CSF) in murine peritoneal macrophages exposed to different stimulators [10 ng/mL of IL-1, 1 microgram/mL of lipopolysaccharide (LPS), and 1 microM N-formyl-methionyl-leucyl-phenylalanine (fMLP)]. Protein tyrosine kinase (PTK) inhibitors attenuated the stimulated superoxide, hydrogen peroxide, and nitric oxide production in macrophages stimulated with IL-1, LPS, or fMLP. N,N-Dimethylsphingosine (DMS) alone stimulated superoxide and hydrogen peroxide production by intact macrophages, but at 45 microM the stimulatory effect on superoxide production was not found. In contrast, DMS attenuated nitric oxide production by macrophages. High concentrations of DMS, tyrphostin, and 2,5-dihydroxycinnamate showed cytotoxic effects. PTK inhibitors did not exhibit a significant effect on granule enzyme release induced by IL-1, whereas they attenuated the effect of LPS and fMLP on degranulation. Genistein and tyrphostin decreased the production of IL-8 and GM-CSF in macrophages activated by IL-1, whereas 2,5-dihydroxycinnamate did not affect it. The results suggest that tyrosine kinases exposed to IL-1, LPS, and fMLP may exert different modulatory actions on macrophage responses. The IL-1-activated macrophage responses, particularly degranulation, appear to be differently regulated by tyrosine kinases compared with the responses activated by LPS and fMLP.

Protective effect of boldine on oxidative mitochondrial damage in streptozotocin-induced diabetic rats

Increased oxidative stress has been suggested to be involved in the pathogenesis and progression of diabetic tissue damage. Several antioxidants have been described as beneficial for oxidative stress-associated diseases. Boldine ([s]-2,9-dihydroxy-1, 10-dimethoxyaporphine) is a major alkaloid found in the leaves and bark of boldo (Peumus boldus Molina), and has been shown to possess antioxidant activity and anti-inflammatory effects. From this point of view, the possible anti-diabetic effect of boldine and its mechanism were evaluated. The experiments were performed on male rats divided into four groups: control, boldine (100 mg kg(-1), daily in drinking water), diabetic [single dose of 80 mg kg(-1)of streptozotocin (STZ), i.p.] and diabetic simultaneously fed with boldine for 8 weeks. Diabetic status was evaluated periodically with changes of plasma glucose levels and body weight in rats. The effect of boldine on the STZ-induced diabetic rats was examined with the formation of malondialdehydes and carbonyls and the activities of endogenous antioxidant enzymes (superoxide dismutase and glutathione peroxidase) in mitochondria of the pancreas, kidney and liver. The scavenging action of boldine on oxygen free radicals and the effect on mitochondrial free-radical production were also investigated. The treatment of boldine attenuated the development of hyperglycemia and weight loss induced by STZ injection in rats. The levels of malondialdehyde (MDA) and carbonyls in liver, kidney and pancreas mitochondria were significantly increased in STZ-treated rats and decreased after boldine administration. The activities of mitochondrial manganese superoxide dismutase (MnSOD) in the liver, pancreas and kidney were significantly elevated in STZ-treated rats. Boldine administration decreased STZ-induced elevation of MnSOD activity in kidney and pancreas mitochondria, but not in liver mitochondria. In the STZ-treated group, glutathione peroxidase activities decreased in liver mitochondria, and were elevated in pancreas and kidney mitochondria. The boldine treatment restored the altered enzyme activities in the liver and pancreas, but not the kidney. Boldine attenuated both STZ- and iron plus ascorbate-induced MDA and carbonyl formation and thiol oxidation in the pancreas homogenates. Boldine decomposed superoxide anions, hydrogen peroxides and hydroxyl radicals in a dose-dependent manner. The alkaloid significantly attenuated the production of superoxide anions, hydrogen peroxide and nitric oxide caused by liver mitochondria. The results indicate that boldine may exert an inhibitory effect on STZ-induced oxidative tissue damage and altered antioxidant enzyme activity by the decomposition of reactive oxygen species and inhibition of nitric oxide production and by the reduction of the peroxidation-induced product formation. Boldine may attenuate the development of STZ-induced diabetes in rats and interfere with the role of oxidative stress, one of the pathogeneses of diabetes mellitus.

Protective effect of harmalol and harmaline on MPTP neurotoxicity in the mouse and dopamine-induced damage of brain mitochondria and PC12 cells

The present study elucidated the protective effect of beta-carbolines (harmaline, harmalol, and harmine) on oxidative neuronal damage. MPTP treatment increased activities of total superoxide dismutase, catalase, and glutathione peroxidase and levels of malondialdehyde and carbonyls in the basal ganglia, diencephalon plus midbrain of brain compared with control mouse brain. Coadministration of harmalol (48 mg/kg) attenuated the MPTP effect on the enzyme activities and formation of tissue peroxidation products. Harmaline, harmalol, and harmine attenuated both the 500 microM MPP(+)-induced inhibition of electron flow and membrane potential formation and the 100 microM dopamine-induced thiol oxidation and carbonyl formation in mitochondria. The scavenging action of beta-carbolines on hydroxyl radicals was represented by inhibition of 2-deoxy-D-ribose degradation. Harmaline and harmalol (100 microM) attenuated 200 microM dopamine-induced viability loss in PC12 cells. The beta-carbolines (50 microM) attenuated 50 microM dopamine-induced apoptosis in PC12 cells. The compounds alone did not exhibit significant cytotoxic effects. The results indicate that beta-carbolines attenuate brain damage in mice treated with MPTP and MPP(+)-induced mitochondrial damage. The compounds may prevent dopamine-induced mitochondrial damage and PC12 cell death through a scavenging action on reactive oxygen species and inhibition of monoamine oxidase and thiol oxidation.

Inhibitory action of thimerosal, a sulfhydryl oxidant, on sodium channels in rat sensory neurons

The effects of thimerosal, a sulfhydryl oxidizing agent, on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) sodium channels in rat dorsal root ganglion neurons were studied using the whole-cell patch clamp technique. Thimerosal blocked the two types of sodium channels in a dose-dependent manner. The inhibitory effect of thimerosal was much more pronounced in TTX-R sodium channels than TTX-S sodium channels. The effect of thimerosal was irreversible upon wash-out with thimerosal-free external solution. However, dithiothreitol, a reducing agent, partially reversed it. Thimerosal shifted the steady-state inactivation curves for both types of sodium channels in the hyperpolarizing direction. The voltage dependence of activation of both types of sodium channels was shifted in the depolarizing direction by thimerosal. The inactivation rate in both types of sodium channels increased after thimerosal treatment. All these effects of thimerosal would add up to cause a depression of sodium channel function leading to a diminished neuronal excitability.

N-Ethylmaleimide modulation of tetrodotoxin-sensitive and tetrodotoxin-resistant sodium channels in rat dorsal root ganglion neurons

The effects of N-ethylmaleimide (NEM), an alkylating reagent to protein sulfhydryl groups, on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) sodium channels in rat dorsal root ganglion (DRG) neurons were studied using the whole cell configuration of patch-clamp technique. When currents were evoked by step depolarizations to 0 mV from a holding potential of -80 mV NEM decreased the amplitude of TTX-S sodium current, but exerted little or no effect on that of TTX-R sodium current. The inhibitory effect of NEM on TTX-S sodium channel was mainly due to the shift of the steady-state inactivation curve in the hyperpolarizing direction. NEM did not affect the voltage-dependence of the activation of TTX-S sodium channel. The steady-state inactivation curve for TTX-R sodium channel was shifted by NEM in the hyperpolarizing direction as that for TTX-S sodium channel. NEM caused a change in the voltage-dependence of the activation of TTX-R sodium channel unlike TTX-S sodium channel. After NEM treatment, the amplitudes of TTX-R sodium currents at test voltages below -10 mV were increased, but those at more positive voltages were not affected. This was explained by the shift in the conductance-voltage curve for TTX-R sodium channels in the hyperpolarizing direction after NEM treatment.

Depressant effects of ambroxol on lipopolysaccharide- or fMLP-stimulated free radical production and granule enzyme release by alveolar macrophages

In order to explore the depressant action of ambroxol, a bronchial expectorant, on the activated alveolar macrophage responses, its effect on lipopolysaccharide (LPS)- or N-formyl-methionyl-leucyl-phenylalanine (fMLP)- stimulated free radical production and granule enzyme release by rat lung alveolar macrophages was investigated. Ambroxol attenuated the 100 ng/ml LPS- or 1 microM fMLP-stimulated superoxide, H(2)O(2)and nitric oxide production and releases of acid phosphatase and lysozyme by alveolar macrophages. Ambroxol attenuated phorbol myristate acetate-stimulated superoxide and nitric oxide production that was inhibited by 100 nM staurosporine. N,N-dimethylsphingosine (DMS, 4.5 and 9 microM) alone stimulated superoxide production by macrophages, while 45 microM of the compound did not show a stimulatory effect. However, DMS decreased nitric oxide production in a dose-dependent manner. Ambroxol did not alter the DMS effect on free radical production that was affected by 10 microM genistein. A preincubation of macrophages with ambroxol (10 and 100 microM), staurosporine and genistein attenuated the elevation of [Ca(2+)](i)caused by LPS. The results suggest that ambroxol exerts a depressant effect on LPS- or fMLP-stimulated free radical production and granule enzyme release by rat alveolar macrophages, which may be attributed to its inhibitory action on the activation process, protein kinase C, but its action on protein tyrosine kinase is not suggested.

Modulation of brain mitochondrial membrane permeability and synaptosomal Ca2+ transport by dopamine oxidation

Effects of dopamine on the membrane permeability transition, thioredoxin reductase activity, production of free radicals and oxidation of sulfhydryl groups in brain mitochondria and the Ca2+ uptake by Na+-Ca2+ exchange and sulfhydryl oxidation in brain synaptosomes were examined. The brain mitochondrial swelling and the fall of transmembrane potential were altered by pretreatment of dopamine in a dose dependent manner. Depressive effect of dopamine on mitochondrial swelling was reversed by 10 microg/ml catalase, and 10 mM DMSO. The activities of thioredoxin reductase in intact or disrupted mitochondria were decreased by dopamine (1-100 microM), 25 microM Zn2+ and 50 microM Mn2+. Dopamine-inhibited enzyme activity was reversed by 10 microg/ml SOD and 10 microg/ml catalase. Pretreatment of dopamine decreased Ca2+ transport in synaptosomes, which was restored by 10 microg/ml SOD and 10 mM DMSO. Dopamine (1-100 microM) in the medium containing mitochondria produced superoxide anion and hydrogen peroxide, while its effect on nitrite production was very weak. The oxidation of sulfhydryl groups in mitochondria and synaptosomes were enhanced by dopamine with increasing incubation times. Results suggest that dopamine could modulate membrane permeability in mitochondria and calcium transport at nerve terminals, which may be ascribed to the action of free radicals and the loss of reduced sulfhydryl groups.

The inhibitory effect of ambroxol on hypochlorous acid-induced tissue damage and respiratory burst of phagocytic cells

Ambroxol (100 microM and 1 mM) and the thiols (all 1 mM), glutathione, tiopronin and cysteine, significantly attenuated the myeloperoxidase, H(2)O(2) and Cl(-) system-caused destruction of alpha(1)-antiproteinase and the HOCl-induced destruction of collagen, whereas they did not affect the elastase-induced destruction of collagen. Glutathione, tiopronin and cysteine almost completely decomposed both HOCl and H(2)O(2), while ambroxol up to 1 mM did not show a scavenging action on H(2)O(2). Ambroxol (1 to 100 microM) and 1 mM thiol compounds markedly inhibited the HOCl-induced alteration of elastase activity. Thiol compounds significantly attenuated the HOCl production caused by degraded immunoglobulin G-activated neutrophils. Ambroxol depressed superoxide and H(2)O(2) production induced by degraded immunoglobulin G-activated neutrophils and by lipopolysaccharide-activated alveolar macrophages in a dose-dependent manner. The results show that ambroxol may interfere with oxidative tissue damage and decrease proteolytic tissue destruction by attenuation of oxidative stress-induced inactivation of alpha(1)-antiproteinase through both decomposition of HOCl and inhibition of the respiratory burst in phagocytic cells.