Publications by authors named "Carine Smith"

45 Publications

Therapeutic application of lantibiotics and other lanthipeptides: old and new findings.

Appl Environ Microbiol 2021 May 7. Epub 2021 May 7.

Division of Clinical Pharmacology, Department Medicine, Stellenbosch University, South Africa.

Lanthipeptides are ribosomally synthesized and post translationally modified peptides, with modifications that are incorporated during biosynthesis by dedicated enzymes. Various modifications of the peptides are possible resulting in a highly diverse group of bioactive peptides that offer a potential reservoir for use in the fight against a plethora of diseases. Their activities range from the antimicrobial properties of lantibiotics, especially against antibiotic-resistant strains, to antiviral activity, immunomodulatory properties, antiallodynic effects and the potential to alleviate cystic fibrosis symptoms. Lanthipeptide biosynthetic genes are widespread within bacterial genomes providing a substantial repository for novel bioactive peptides. Using genome mining tools novel bioactive lanthipeptides can be identified and coupled with rapid screening and heterologous expression technologies the lanthipeptide drug discovery pipeline can be significantly sped up. Lanthipeptides represents a group of bioactive peptides that holds great potential as biotherapeutics, especially at a time when novel and more effective therapies are required.With this review we provide insight into the latest developments made towards the therapeutic applications and production of lanthipeptides, specifically looking at heterologous expression systems.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/AEM.00186-21DOI Listing
May 2021

Targeting Stem Cells in Chronic Inflammatory Diseases.

Adv Exp Med Biol 2021 ;1286:163-181

Department of Physiological Sciences, Science Faculty, Stellenbosch University, Stellenbosch, South Africa.

Mesenchymal stem cell (MSC) dysfunction is a serious complication in ageing and age-related inflammatory diseases such as type 2 diabetes mellitus. Inflammation and oxidative stress-induced cellular senescence alter the immunomodulatory ability of MSCs and hamper their pro-regenerative function, which in turn leads to an increase in disease severity, maladaptive tissue damage and the development of comorbidities. Targeting stem/progenitor cells to restore their function and/or protect them against impairment could thus improve healing outcomes and significantly enhance the quality of life for diabetic patients. This review discusses the dysregulation of MSCs' immunomodulatory capacity in the context of diabetes mellitus and focuses on intervention strategies aimed at MSC rejuvenation. Research pertaining to the potential therapeutic use of either pharmacological agents (NFкB antagonists), natural products (phytomedicine) or biological agents (exosomes, probiotics) to improve MSC function is discussed and an overview of the most pertinent methodological considerations given. Based on in vitro studies, numerous anti-inflammatory agents, antioxidants and biological agents show tremendous potential to revitalise MSCs. An integrated systems approach and a thorough understanding of complete disease pathology are however required to identify feasible candidates for in vivo targeting of MSCs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/978-3-030-55035-6_12DOI Listing
March 2021

The trace aminergic system: a gender-sensitive therapeutic target for IBS?

J Biomed Sci 2020 Sep 28;27(1):95. Epub 2020 Sep 28.

Department of Physiological Sciences, Stellenbosch University, Stellenbosch Private Bag X1, Stellenbosch, 7062, South Africa.

Due to a lack of specific or sensitive biomarkers, drug discovery advances have been limited for individuals suffering from irritable bowel syndrome (IBS). While current therapies provide symptomatic relief, inflammation itself is relatively neglected, despite the presence of chronic immune activation and innate immune system dysfunction. Moreover, considering the microgenderome concept, gender is a significant aetiological risk factor. We believe that we have pinpointed a "missing link" that connects gender, dysbiosis, diet, and inflammation in the context of IBS, which may be manipulated as therapeutic target. The trace aminergic system is conveniently positioned at the interface of the gut microbiome, dietary nutrients and by-products, and mucosal immunity. Almost all leukocyte populations express trace amine associated receptors and significant amounts of trace amines originate from both food and the gut microbiota. Additionally, although IBS-specific data are sparse, existing data supports an interpretation in favour of a gender dependence in trace aminergic signalling. As such, trace aminergic signalling may be altered by fluctuations of especially female reproductive hormones. Utilizing a multidisciplinary approach, this review discusses potential mechanisms of actions, which include hyperreactivity of the immune system and aberrant serotonin signalling, and links outcomes to the symptomology clinically prevalent in IBS. Taken together, it is feasible that the additional level of regulation by the trace aminergic system in IBS has been overlooked, until now. As such, we suggest that components of the trace aminergic system be considered targets for future therapeutic action, with the specific focus of reducing oxidative stress and inflammation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12929-020-00688-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7520957PMC
September 2020

D-galactose: a model of accelerated ageing sufficiently sensitive to reflect preventative efficacy of an antioxidant treatment.

Biogerontology 2020 12 7;21(6):745-761. Epub 2020 Jul 7.

Department of Physiological Sciences, Science Faculty, Stellenbosch University, Stellenbosch, South Africa.

Considering that the phenomenon of accelerated ageing contributes to early onset of various chronic diseases, modelling of the relevant dysregulated systems or responses is vital for research aimed at identification of potential therapeutic targets. Here, we aimed to establish a model capable of simulating the redox and inflammatory changes of accelerated ageing-specifically, the aim was early phase accelerated ageing, which would allow therapeutic intervention in a preventative approach prior to clinical disease manifestation. A secondary aim was to evaluate the sensitivity of the model to reflect preventative treatment efficacy. Daily D-galactose injections (250 mg/kg body mass/day) for 8 weeks in 9-week-old male Wistar rats induced a model of early accelerated ageing (decreased plasma FRAP; P < 0.05 and altered inflammatory signalling) and an aged profile in lymph node ultrastructure, but did not yet result in telomere shortening. Preventative daily oral antioxidant administration (grape seed-derived polyphenol, 100 mg/kg body mass) prevented tissue ageing, beneficially modulated the inflammatory response, including neutrophil chemokinetic capacity, and tended to increase absolute telomere length. Data suggests that using a mild model of D-galactose administration than those employed to induce neurodegeneration, simulated the point where oxidative stress starts to overwhelm the endogenous antioxidant response and where a pro-inflammatory phenotype switch manifests. Furthermore, despite the expected small effect size, the model was sufficiently sensitive to reflect benefits of preventative antioxidant treatment in the context of ageing. This model presents a practical model for use in drug discovery, particularly in the context of preventative medicine aimed at limiting oxidative stress-associated ageing. Since this starting point of accelerated ageing as illustrated by current data, is not expected to reflect major ageing-associated changes yet, we recommend that future preventative drug discovery studies employ a longitudinal study design in order to clearly demonstrate the delay of this starting point by preventative strategies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10522-020-09891-xDOI Listing
December 2020

Anxiety: An overlooked confounder in the characterisation of chronic stress-related conditions?

PLoS One 2020 16;15(4):e0230053. Epub 2020 Apr 16.

Department of Physiological Sciences, Science Faculty, Stellenbosch University, Stellenbosch, South Africa.

Although anxiety disorders are among the most prevalent of psychiatric disorders, childhood trauma-related studies seldom consider anxiety proneness as distinct aetiological contributor. We aimed to distinguish between trauma- and anxiety-associated physiological profiles. South African adolescent volunteers were categorised for trauma exposure (CTQ, mean score 39±11) and anxiety proneness (AP)(CASI, mean score 37±7, STAI-T, mean score 41±8). Circulating hormone and leukocyte glucocorticoid receptor levels, as well as leukocyte functional capacity, were assessed. AP was associated with lower DHEAs (P<0.05) and higher leukocyte GR expression (P<0.05). DHEAs was also negatively correlated with anxiety sensitivity (CASI, P<0.05). In conclusion, AP may have more predictive power than trauma in terms of health profile. Increased glucocorticoid sensitivity previously reported after trauma, may be a unique function of anxiety and not trauma exposure per se. DHEAs concentration was identified as potentially useful marker for monitoring progressive changes in HPA-axis sensitivity and correlated with psychological measures of anxiety.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0230053PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7162495PMC
June 2020

Exposure to Maternal Chronic Inflammation Transfers a Pro-Inflammatory Profile to Generation F2 via Sex-Specific Mechanisms.

Front Immunol 2020 13;11:48. Epub 2020 Feb 13.

Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa.

Generational transfer of maladaptations in offspring have been reported to persist for multiple generations in conditions of chronic inflammation, metabolic and psychological stress. Thus, the current study aimed to expand our understanding of the nature, potential sex specificity, and transgenerational plasticity of inflammatory maladaptations resulting from maternal chronic inflammation. Briefly, F1 and F2 generations of offspring from C57/BL/6 dams exposed to a modified maternal periconception systemic inflammation (MSPI) protocol were profiled in terms of leukocyte and splenocyte counts and cytokine responses, as well as glucocorticoid sensitivity. Overall, F1 male and female LPS groups presented with glucocorticoid hypersensitivity (with elevated corticosterone and increased leukocyte glucocorticoid receptor levels) along with a pro-inflammatory phenotype, which carried over to the F2 generation. The transfer of inflammatory and glucocorticoid responsiveness from F1 to F2 is evident, with heritability of this phenotype in F2. The findings suggest that maternal (F0) perinatal chronic inflammation resulted in glucocorticoid dysregulation and a resultant pro-inflammatory phenotype, which is transferred in the maternal lineage but seems to affect male offspring to a greater extent. Of further interest, upregulation of IL-1β cytokine responses is reported in female offspring only. The cumulative maladaptation reported in F2 offspring when both F1 parents were affected by maternal LPS exposure is suggestive of immune senescence. Given the potential impact of current results and the lack of sex-specific investigations, more research in this context is urgently required.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fimmu.2020.00048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7031653PMC
February 2021

Functional Expression of GFP-Fused Class I Lanthipeptides in .

ACS Synth Biol 2019 10 25;8(10):2220-2227. Epub 2019 Sep 25.

Department of Physiological Sciences , Stellenbosch University , Matieland 7602 , South Africa.

Lanthipeptides are ribosomally synthesized and post-translationally modified peptides, with several having antimicrobial activity. The biosynthetic machinery responsible for modification of the class I lanthipeptide nisin provides a means for modification of a diverse range of lanthipeptides. However, literature regarding expression of class I lanthipeptides in a malleable Gram-negative host such as is limited. Here, we coexpressed precursor class I lanthipeptides fused to green fluorescent protein (GFP) along with the dehydratase and cyclase from the nisin operon. Fusion to GFP did not interfere with post-translational modifications as antimicrobially active nisin could be proteolytically liberated from the expressed GFP fusion. Additionally, we used this system to express two other class I lanthipeptides precursors fused to GFP (Pep5 and epilancin 15X), although only Pep5 exhibited consistent antimicrobial activity. This is the first report of a GFP-based fusion expression system for the expression of class I lanthipeptides in . The GFP-based fusion expression system is a robust system with the advantage of directly visualizing expression and purification through GFP fluorescence.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acssynbio.9b00167DOI Listing
October 2019

Migration of Bacteriocins Across Gastrointestinal Epithelial and Vascular Endothelial Cells, as Determined Using In Vitro Simulations.

Sci Rep 2019 08 7;9(1):11481. Epub 2019 Aug 7.

Department of Microbiology, Stellenbosch University, Stellenbosch, 7600, South Africa.

Little is known about the migration of bacteriocins across human cells. In this study, we report on migration of three bacteriocins nisin, plantaricin 423 and bacST4SA across colonic adenocarcinoma (Caco-2) cells and human umbilical vein endothelial cells (HUVECs). Bacteriocins were fluorescently labelled while still maintaining antimicrobial activity. Migration of fluorescently labelled bacteriocins across monolayers was assessed in vitro using transmigration well inserts. After 3 h, 75% of nisin, 85% of plantaricin 423 and 82% of bacST4SA migrated across the Caco-2 cell monolayer. Over the same time span, 88% nisin, 93% plantaricin 423 and 91% bacST4SA migrated across the HUVEC monolayer. The viability of both cell types remained unchanged when exposed to 50 µM of nisin, plantaricin 423 or bacST4SA. The effect of human plasma on bacteriocin activity was also assessed. Activity loss was dependent on bacteriocin type and concentration, with the class-IIa bacteriocins retaining more activity compared to nisin. This is the first report of bacteriocins migrating across simulated gastrointestinal- and vascular-barriers. This study provides some of the first evidence that bacteriocins are capable of crossing the gut-blood-barrier. However, in vivo studies need to be performed to confirm these findings and expand on the role of bacteriocin migration across cell barriers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-019-47843-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6685951PMC
August 2019

Root extracellular traps versus neutrophil extracellular traps in host defence, a case of functional convergence?

Biol Rev Camb Philos Soc 2019 10 27;94(5):1685-1700. Epub 2019 May 27.

Institute for Wine Biotechnology, Department of Viticulture and Oenology, Faculty of AgriSciences, Stellenbosch University, Matieland, 7602, South Africa.

The root cap releases cells that produce massive amounts of mucilage containing polysaccharides, proteoglycans, extracellular DNA (exDNA) and a variety of antimicrobial compounds. The released cells - known as border cells or border-like cells - and mucilage secretions form networks that are defined as root extracellular traps (RETs). RETs are important players in root immunity. In animals, phagocytes are some of the most abundant white blood cells in circulation and are very important for immunity. These cells combat pathogens through multiple defence mechanisms, including the release of exDNA-containing extracellular traps (ETs). Traps of neutrophil origin are abbreviated herein as NETs. Similar to phagocytes, plant root cap-originating cells actively contribute to frontline defence against pathogens. RETs and NETs are thus components of the plant and animal immune systems, respectively, that exhibit similar compositional and functional properties. Herein, we describe and discuss the formation, molecular composition and functional similarities of these similar but different extracellular traps.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/brv.12522DOI Listing
October 2019

C-Reactive Protein Is Elevated Only in High Creatine Kinase Responders to Muscle Damaging Exercise.

Front Physiol 2019 11;10:86. Epub 2019 Feb 11.

Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa.

The purpose of this study was to investigate if exertional rhabdomyolysis induced by an acute bout of plyometric exercise in untrained individuals was associated with histological characteristics of skeletal muscle, creatine kinase (CK) polymorphism or secondary damage. Twenty-six healthy male untrained individuals completed a bout of plyometric exercise (10 sets of 10 maximal squat jumps, with each standardized to achieve at least 95% of individual maximal jump height). Blood samples were taken, and perceived pain was scored immediately before the exercise intervention and 6 h, 1, 2, and 3 days post-intervention. Muscle biopsies were collected 9 or 4 days before (baseline) and 3 days after plyometric jumps. Subjects were divided into two groups, high ( = 10) and low responders ( = 16), based on a cut-off limit for exertional rhabdomyolysis of peak CK activity ≥ 1000 U/L in any post-exercise blood sample. Perceived pain was more severe assessed in squat than standing position. Low responders perceived more pain at 6 h and 1 day, while high responders perceived more pain than low responders on days three and four after exercise; structural (dystrophin staining) and ultra-structural (transmission electron microscopy) analysis of muscle fibers revealed no baseline pathology; damage was evident in all individuals in both groups, with no difference between high and low responders in either damage or fiber type proportion. High responders had significantly higher total white blood cell and neutrophil counts 6 h and significantly higher C-reactive protein (CRP) 6 h and days one and two after exercise compared to low responders. High responders had significantly greater muscle myeloperoxidase (MPO) levels in baseline and 3 day post-exercise biopsies compared to baseline of low responders. MLCK C49T single polymorphism was present in 26% of volunteers, whose CK responses were not higher than those with MLCK CC or CT genotype. In conclusion, perceived pain is more effectively assessed with potentially affected muscle under eccentric strain, even if static. High CK responders also have pronounced CRP responses to unaccustomed plyometric exercise intervention. Exertional rhabdomyolysis after unaccustomed eccentric exercise may be related to underlying inability to resolve intramuscular MPO.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fphys.2019.00086DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6378920PMC
February 2019

Harnessing Macrophages for Controlled-Release Drug Delivery: Lessons From Microbes.

Front Pharmacol 2019 25;10:22. Epub 2019 Jan 25.

Department of Physiological Sciences, Stellenbosch University, Matieland, South Africa.

With the effectiveness of therapeutic agents ever decreasing and the increased incidence of multi-drug resistant pathogens, there is a clear need for administration of more potent, potentially more toxic, drugs. Alternatively, biopharmaceuticals may hold potential but require specialized protection from premature degradation. Thus, a paralleled need for specialized drug delivery systems has arisen. Although cell-mediated drug delivery is not a completely novel concept, the few applications described to date are not yet ready for application, for various reasons such as drug-induced carrier cell death, limited control over the site and timing of drug release and/or drug degradation by the host immune system. Here, we present our hypothesis for a new drug delivery system, which aims to negate these limitations. We propose transport of nanoparticle-encapsulated drugs autologous macrophages polarized to M1 phenotype for high mobility and treated to induce transient phagosome maturation arrest. In addition, we propose a significant shift of existing paradigms in the study of host-microbe interactions, in order to study microbial host immune evasion and dissemination patterns for their therapeutic utilization in the context of drug delivery. We describe a system in which microbial strategies may be adopted to facilitate absolute control over drug delivery, and without sacrificing the host carrier cells. We provide a comprehensive summary of the lessons we can learn from microbes in the context of drug delivery and discuss their feasibility for therapeutic application. We then describe our proposed "synthetic microbe drug delivery system" in detail. In our opinion, this multidisciplinary approach may hold the solution to effective, controlled drug delivery.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fphar.2019.00022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6355695PMC
January 2019

Polyphenol-associated oxidative stress and inflammation in a model of LPS-induced inflammation in glial cells: do we know enough for responsible compounding?

Inflammopharmacology 2019 Feb 13;27(1):189-197. Epub 2018 Dec 13.

Department Physiological Sciences, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa.

Cyanidin and chlorogenic acid are polyphenols from plant origin that are present in many common fruits, particularly in berries. To corroborate the protective or detrimental effects of both compounds from a neuro-inflammatory perspective, in vitro experiments were carried out in human astrocytes (U-373). Astrocytes were pre-treated with a range of concentrations of either cyanidin, chlorogenic acid or a combined treatment for a period of 30 min, before exposure to Escherichia coli lipopolysaccharide (LPS) challenge for 23.5 h, after which cytotoxicity (propidium iodide exclusion assay), cytoprotective effects (XTT assay) and effects on functional capacity (secretion of pro-inflammatory cytokines IL-6 and MCP-1) were evaluated. No treatment resulted in cytotoxicity, but high dose (20 µg/mL) LPS significantly reduced mitochondrial reductive capacity (p < 0.001). This effect was prevented in a dose-dependent manner by both cyanidin and chlorogenic acid, as well as by the combination treatment. However, in the absence of LPS, IL-6 secretion was significantly increased in response to 2 µM of either cyanidin or chlorogenic acid (both p < 0.0001), as well as the combination treatment (p < 0.01). MCP-1 secretion followed a similar trend, but did not reach statistical significance. Although we acknowledge the requirement for in vivo investigations to validate our interpretations, current data highlight the potential risk for antioxidant toxicity that is linked to high dose supplementation with single compound antioxidants. Research focused at elucidating synergistic effects between different antioxidants is required to minimise risk of adverse effects.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10787-018-0549-yDOI Listing
February 2019

Corrigendum: A Review: The Fate of Bacteriocins in the Human Gastro-Intestinal Tract: Do They Cross the Gut-Blood Barrier?

Front Microbiol 2018 30;9:2938. Epub 2018 Nov 30.

Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa.

[This corrects the article DOI: 10.3389/fmicb.2018.02297.].
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fmicb.2018.02938DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6284148PMC
November 2018

A Review: The Fate of Bacteriocins in the Human Gastro-Intestinal Tract: Do They Cross the Gut-Blood Barrier?

Front Microbiol 2018 28;9:2297. Epub 2018 Sep 28.

Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa.

The intestinal barrier, consisting of the vascular endothelium, epithelial cell lining, and mucus layer, covers a surface of about 400 m. The integrity of the gut wall is sustained by transcellular proteins forming tight junctions between the epithelial cells. Protected by three layers of mucin, the gut wall forms a non-permeable barrier, keeping digestive enzymes and microorganisms within the luminal space, separate from the blood stream. Microorganisms colonizing the gut may produce bacteriocins in an attempt to outcompete pathogens. Production of bacteriocins in a harsh and complex environment such as the gastro-intestinal tract (GIT) may be below minimal inhibitory concentration (MIC) levels. At such low levels, the stability of bacteriocins may be compromised. Despite this, most bacteria in the gut have the ability to produce bacteriocins, distributed throughout the GIT. With most antimicrobial studies being performed , we know little about the migration of bacteriocins across epithelial barriers. The behavior of bacteriocins in the GIT is studied , using models, flow cells, or membranes resembling the gut wall. Furthermore, little is known about the effect bacteriocins have on the immune system. It is generally believed that the peptides will be destroyed by macrophages once they cross the gut wall. Studies done on the survival of neurotherapeutic peptides and their crossing of the brain-blood barrier, along with other studies on small peptides intravenously injected, may provide some answers. In this review, the stability of bacteriocins in the GIT, their effect on gut epithelial cells, and their ability to cross epithelial cells are discussed. These are important questions to address in the light of recent papers advocating the use of bacteriocins as possible alternatives to, or used in combination with, antibiotics.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fmicb.2018.02297DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6173059PMC
September 2018

Aspalathus linearis (Rooibos) - a functional food targeting cardiovascular disease.

Food Funct 2018 Oct;9(10):5041-5058

Dept Physiological Sciences, Science Faculty, Stellenbosch University, Stellenbosch, South Africa.

Increasing consumer bias toward natural products and the considerable wealth of indigenous knowledge has precipitated an upturn in market-driven research into potentially beneficial medicinal plants. In this context, Aspalathus linearis (Rooibos) has been identified to be a promising candidate which may impact cardiovascular disease (CVD), which is one of the most widely studied chronic diseases of modern times. Despite these efforts, ischemic heart disease remains the number one cause of mortality globally. Apart from genetic predisposition and other aetiological mechanisms specific to particular types of CVD, co-factors from interlinked systems contribute significantly to disease development and the severity of its clinical manifestation. The bioactivity of Rooibos is directed towards multiple therapeutic targets. Experimental data to date include antioxidant, anti-inflammatory and anti-diabetic effects, as well as modulatory effects in terms of the immune system, adrenal steroidogenesis and lipid metabolism. This review integrates relevant literature on the therapeutic potential of Rooibos in the context of CVD, which is currently the most common of non-communicable diseases. The therapeutic value of whole plant extracts versus isolated active ingredients are addressed, together with the potential for overdose or herb-drug interaction. The body of research undertaken to date clearly underlines the benefits of Rooibos as both preventative and complementary therapeutic functional food in the context of CVD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c8fo01010bDOI Listing
October 2018

Grape polyphenols corrects ageing-related detriments in neutrophil functionality via modulation of specific molecular targets.

Inflammopharmacology 2018 Oct 27;26(5):1349-1358. Epub 2018 Jun 27.

Department of Physiological Sciences, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa.

Oxidative stress and inflammation are intricately interlinked as aetiological factors in the context of ageing and chronic disease-related accelerated ageing. Previous research by our group has highlighted the anti-oxidant and anti-inflammatory potential of grape-derived polyphenols in the context of acute inflammation and oxidative stress. The aim here was to add to this by assessing efficacy of the treatment (acutely) to address ageing-associated cumulative pro-oxidant and pro-inflammatory changes in an in vitro model. Blood from young and aged humans was analysed for baseline oxidative stress and inflammatory status. Isolated neutrophils were acutely exposed to the polyphenol treatment in vitro. The chemokinetic capacity of treated and control neutrophils in response to fMLP was subsequently determined in a Dunn chamber, using live cell imaging. Neutrophils were also analysed for the expression of selected molecular markers associated with functional capacity and oxidative stress. Results indicate that the aged population had significantly worse oxidative stress and inflammatory profiles (higher plasma conjugated dienes and MPO) than young controls. Neutrophils isolated from both young and aged individuals had improved chemokinetic accuracy and capacity after in vitro polyphenol treatment. Additionally, increased shedding of CD16 and expression of CD66b suggested sites via which the polyphenol achieved improved neutrophil motility. We conclude that grape seed-derived polyphenols facilitated improved neutrophil functionality by acting on the molecular targets elucidated here.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10787-018-0511-zDOI Listing
October 2018

Regulation of redox status in neuronal SH-SY5Y cells by blueberry (Vaccinium myrtillus L.) juice, cranberry (Vaccinium macrocarpon A.) juice and cyanidin.

Food Chem Toxicol 2018 Aug 1;118:572-580. Epub 2018 Jun 1.

Department of Pharmacology, Pharmacognosy and Botany, Faculty of Pharmacy, Universidad Complutense de Madrid, 28040 Madrid, Spain.

Blueberry and cranberry are fruits with high polyphenol content, particularly anthocyanins. As cyanidin derivatives have been identified as one of the most representative polyphenols in berry juices, cyanidin has been designated for a better comparison and understanding of the potential neuroprotection of juices obtained from two Vaccinium species. Neuroblastoma SH-SY5Y cells were previously treated with different concentrations of lyophilized blueberry juice, cranberry juice or cyanidin for 24 h and oxidative stress was then generated with hydrogen peroxide (100 μM) for 30 min. Cytoprotective properties of cranberry juice, blueberry juice or cyanidin were evaluated using different methodologies such as mitochondrial activity (MTT), TBARS and ROS production, antioxidant enzymes (CAT, SOD) and antioxidant properties (ORAC, FRAP). Results indicated that blueberry and cranberry juices as well as cyanidin increased mitochondrial activity and reduced intracellular ROS production and lipid peroxidation induced by hydrogen peroxide. Furthermore, these berry juices and cyanidin upregulated the activity of the antioxidant enzymes catalase and superoxide dismutase. Finally, in vitro antioxidant capacities were confirmed by ORAC and FRAP assays demonstrating the potential of cyanidin and cyanidin-containing products for pharmaceutical or nutritional applications to prevent oxidative stress in neuronal cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.fct.2018.05.066DOI Listing
August 2018

Natural antioxidants in prevention of accelerated ageing: a departure from conventional paradigms required.

Authors:
Carine Smith

J Physiol Biochem 2018 Nov 14;74(4):549-558. Epub 2018 Mar 14.

Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa.

The modern lifestyle is characterised by various factors that cause accelerating ageing by the upregulation of oxidative stress and inflammation-two processes that are inextricably linked in an endless circle of self-propagation. Inflammation in particular is commonly accepted as aetiological factor in many chronic disease states, such as obesity, diabetes and depression. In terms of disease prevention or treatment, interventions aimed at changing dietary and/or exercise habits have had limited success in practise, mostly due to poor long-term compliance. Furthermore, other primary stimuli responsible for eliciting an oxidative stress or inflammatory response-e.g. psychological stress and anxiety-cannot always be easily addressed. Thus, preventive medicine aimed at countering the oxidative stress and/or inflammatory responses has become of interest. Especially in developing countries, such as South Africa, the option of development of effective strategies from plants warrants further investigation. A brief overview of the most relevant and promising South African plants which have been identified in the context of inflammation, oxidative stress and chronic disease is provided here. In addition, and more specifically, our group and others have shown considerable beneficial effects across many models, after treatment with products derived from grapes. Of particular interest, specific cellular mechanisms have been identified as therapeutic targets of grape-derived polyphenols in the context of inflammation and oxidative stress. The depth of these studies afforded some additional insights, related to methodological considerations pertaining to animal vs. human models in natural product research, which may address the current tendency for generally poor translation of positive animal model results into human in vivo models. The importance of considering individual data vs. group averages in this context is highlighted.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s13105-018-0621-5DOI Listing
November 2018

Caffeine Improves Triathlon Performance: A Field Study in Males and Females.

Int J Sport Nutr Exerc Metab 2018 May 1;28(3):228-237. Epub 2018 Jun 1.

1 Stellenbosch University.

The ergogenic effect of caffeine on endurance exercise is commonly accepted. We aimed to elucidate realistically the effect of caffeine on triathlon event performance using a field study design, while allowing investigation into potential mechanisms at play. A double-blind, randomized, crossover field trial was conducted. Twenty-six triathletes (14 males and 12 females; mean ± SD: age = 37.8 ± 10.6 years, habitual caffeine intake = 413 ± 505 mg/day, percentage body fat = 14.5 ± 7.2%, and training/week = 12.8 ± 4.5 hr) participated in this study. Microencapsulated caffeine (6 mg/kg body weight) was supplemented 60 min pretrial. Performance data included time to completion, rating of perceived exertion, and profile of mood states. Blood samples taken before, during, and postrace were analyzed for cortisol, testosterone, and full blood count. Capillary blood lactate concentrations were assessed prerace, during transitions, and 3, 6, 9, 12, and 15 min after triathlons. Caffeine supplementation resulted in a 3.7% reduction in swim time (33.5 ± 7.0 vs. 34.8 ± 8.1 min, p < .05) and a 1.3% reduction in time to completion (149.6 ± 19.8 vs. 151.5 ± 18.6 min, p < .05) for the whole group. Gender differences and individual responses are also presented. Caffeine did not alter the rating of perceived exertion significantly, but better performance after caffeine supplementation suggests a central effect resulting in greater overall exercise intensity at the same rating of perceived exertion. Caffeine supplementation was associated with higher postexercise cortisol levels (665 ± 200 vs. 543 ± 169 nmol/L, p < .0001) and facilitated greater peak blood lactate accumulation (analysis of variance main effect, p < .05). We recommend that triathlon athletes with relatively low habitual caffeine intake may ingest 6 mg/kg body weight caffeine, 45-60 min before the start of Olympic-distance triathlon to improve their performance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1123/ijsnem.2017-0165DOI Listing
May 2018

Immunomodulatory effects of Sceletium tortuosum (Trimesemine™) elucidated in vitro: Implications for chronic disease.

J Ethnopharmacol 2018 Mar 16;214:134-140. Epub 2017 Dec 16.

Department of Physiological Sciences, Science Faculty, Stellenbosch University, Stellenbosch, South Africa. Electronic address:

Ethnopharmacological Relevance: Sceletium tortuosum, among other Sceletium species, was traditionally used by the Khoisan people of Southern Africa for relief of pain-related ailments. However, the commercial availability of this supplement has greatly expanded due to anecdotal claims of its mood-elevating and anxiolytic properties. Unrelated research has elucidated a significant link between cytokines and the mediation of depression. Therefore, the effect of Sceletium supplementation on immune cell functionality is of interest, since the efficacy of potential depression treatments could, at least in part, rely on downregulation of pro-inflammatory signalling.

Aim Of The Study: The current study evaluated the immunomodulatory effects of a Sceletium extract, both basally and in the context of acute endotoxin stimulation.

Materials And Methods: Primary human monocytes were supplemented with either a 0.01mg/ml or 1mg/ml Sceletium extract dose, with or without E. coli LPS stimulation in vitro, for 24h. Mitochondrial viability, as an indirect measure of cytotoxicity, and cytokine release in response to the treatment intervention were assessed.

Results: Sceletium extract treatment was associated with increased mitochondrial viability, as well as up-regulated IL-10 release under basal conditions. LPS exposure significantly decreased mitochondrial viability, but this was prevented completely under Sceletium-treated conditions. The acute inflammatory response to LPS stimulation was not negatively affected. Sceletium treatment conferred most significant effects at a dose of 0.01mg/ml.

Conclusions: Sceletium exerts significant cytoprotective effects in the setting of endotoxin stimulation. Cytokine assessment indicated that Sceletium possesses mild anti-inflammatory properties, but does not hinder the mounting of an adequate immune response to acute immune challenge. These findings indicate that Sceletium may be beneficial for the attenuation of cytokine-induced depression, as well as in systemic low-grade inflammation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jep.2017.12.020DOI Listing
March 2018

Development of a transendothelial shuttle by macrophage modification.

J Tissue Eng Regen Med 2018 04 28;12(4):e1889-e1898. Epub 2017 Dec 28.

Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa.

One of the limiting factors in tissue regeneration, particularly in the context of chronic disease such as myodystrophy, motor neuron disease, sarcopenia, and cardiovascular disease, is limited availability of stem cells. We propose employing autologous macrophages to deliver stem cells, thereby facilitating tissue regeneration, by a novel and relatively non-invasive therapeutic intervention. Circulatory monocytic cells of M1 phenotype have capacity for transendothelial migration to infiltrate damaged tissue, making them ideal delivery vehicles. However, in order to deliver viable stem cells, these macrophages must undergo phagosome maturation arrest. Our aim was to induce phagosome maturation arrest in prepolarised M1 macrophages, whilst maintaining capacity for phagocytic engulfment (including phagosome formation) and transendothelial migration. Primary human M1 macrophages were treated with a wortmannin-concanamycin A-chloroquine cocktail to induce arrest. Modified cells were allowed to ingest 4.5 μm protein-coated fluorescent latex beads (simulated stem cells), before migratory capacity in response to MCP-1 was assessed over a 2-hr period in a Transwell co-culture system. Data indicate that phagosome acidification (as indicated by pHrodo®) was prevented in treated cells, effectively limiting digestion of ingested "cargo" (1.23 ± 0.26% vs. 7.52 ± 0.98% in controls; p < .0001). Neither phagocytic engulfment capacity (68.67 ± 3.51% vs. 61.19 ± 4.68%) nor migratory capacity (70.14 ± 12.6 vs. 72.86 ± 16.0 migrated cells per well) was compromised. We conclude that macrophages were successfully modified into transendothelial delivery vehicles, without compromising required functionality. This delivery system can be exploited to develop a novel method for focussed stem cell and/or drug delivery.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/term.2620DOI Listing
April 2018

Anthocyanin profile, antioxidant activity and enzyme inhibiting properties of blueberry and cranberry juices: a comparative study.

Food Funct 2017 Nov;8(11):4187-4193

Department of Pharmacy, Faculty of Health Sciences, Universidad San Jorge, 50.830 Villanueva de Gállego, Zaragoza, Spain.

Cranberry (Vaccinium macrocarpon) and blueberry (Vaccinium myrtillus) juices are commonly consumed as a source of antioxidants. The aim of this study was to compare bioactivities as well as the differences in the polyphenol content and anthocyanin profile of both juices. Polyphenol and anthocyanin contents were quantified using spectrophotometric and chromatographic methods. Bioassays were carried out in terms of antioxidant properties in cell and cell free systems as well as inhibition of physiological enzymes that are targets involved in the prevention of chronic diseases (monoamine oxidase A, tyrosinase, acetylcholinesterase, α-glucosidase and dipeptidyl peptidase-4). Both juices contained a significant amount of anthocyanins (3.909 mg anthocyanins per mg extract for blueberry juice and 0.398 for cranberry juice) and also exhibited antioxidant properties against DPPH, superoxide radicals and hydrogen peroxide. These juices showed inhibitory effects on the enzymes, showing substantial potential as antioxidant, neuroprotective and anti-hyperglycaemic agents. The total anthocyanin and polyphenol content was higher in blueberry juice, which is indicative of a higher antioxidant activity. Both juices were also able to inhibit monoamine oxidase A, tyrosinase, α-glucosidase and dipeptidyl peptidase-4 in a dose-dependent manner. However, cranberry juice had a greater capacity than blueberry juice as an α-glucosidase inhibitor, revealing a similar activity to acarbose.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c7fo01205eDOI Listing
November 2017

Bioactive and functional properties of sour cherry juice (Prunus cerasus).

Food Funct 2016 Nov;7(11):4675-4682

Department of Pharmacy, Faculty of Health Sciences, Universidad San Jorge, 50.830 Villanueva de Gállego, Zaragoza, Spain.

Sour cherry juice (Prunus cerasus) is consumed as a nutritional supplement claiming health effects. The aim of the study was to evaluate the different properties of sour cherry juice in terms of antioxidant activity and inhibition of target enzymes in the central nervous system and diabetes. The content of polyphenols and anthocyanins was quantified. Different experiments were carried out to determine the radical scavenging properties of the juice. The activity of sour cherry juice was also tested in physiological relevant enzymes of the central nervous system (acetylcholinesterase, monoamine oxidase A, tyrosinase) and others involved in type 2 diabetes (α-glucosidase, dipeptidyl peptidase-4). Sour cherry juice showed significant antioxidant effects but the activity of the lyophilized juice was not superior to compounds such as ascorbic, gallic or chlorogenic acid. Furthermore, sour cherry juice and one of its main polyphenols known as chlorogenic acid were also able to inhibit monoamine oxidase A and tyrosinase as well as enzymes involved in diabetes. This is the first time that sour cherry juice is reported to inhibit monoamine oxidase A, α-glucosidase and dipeptidyl peptidase-4 in a dose dependent manner, which may be of interest for human health and the prevention of certain diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c6fo01295gDOI Listing
November 2016

Efficacy of Lantibiotic Treatment of Staphylococcus aureus-Induced Skin Infections, Monitored by In Vivo Bioluminescent Imaging.

Antimicrob Agents Chemother 2016 07 20;60(7):3948-55. Epub 2016 Jun 20.

Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa

Staphylococcus aureus is a bacterial pathogen responsible for the majority of skin and soft tissue infections. Antibiotics are losing their efficacy as treatment for skin and soft tissue infections as a result of increased resistance in a variety of pathogens, including S. aureus It is thus imperative to explore alternative antimicrobial treatments to ensure future treatment options for skin and soft tissue infections. A select few lantibiotics, a group of natural defense peptides produced by bacteria, inhibit the growth of numerous clinical S. aureus isolates, including methicillin-resistant strains. In this study, the antimicrobial activities of nisin, clausin, and amyloliquecidin, separately administered, were compared to that of a mupirocin-based ointment, which is commonly used as treatment for S. aureus-induced skin infections. Full-thickness excisional wounds, generated on the dorsal surfaces of mice, were infected with a bioluminescent strain of S. aureus (strain Xen 36). The infections were monitored in real time using in vivo bioluminescent imaging. Lantibiotic treatments significantly reduced the bioluminescence of S. aureus Xen 36 to a level similar to that recorded with mupirocin treatment. Wound closure, however, was more pronounced during lantibiotic treatment. Lantibiotics thus have the potential to be used as an alternative treatment option for S. aureus-induced skin infections.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/AAC.02938-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4914678PMC
July 2016

High-mesembrine Sceletium extract (Trimesemine™) is a monoamine releasing agent, rather than only a selective serotonin reuptake inhibitor.

J Ethnopharmacol 2016 Jan 23;177:111-6. Epub 2015 Nov 23.

Department of Physiological Sciences, Science Faculty, Stellenbosch University, Stellenbosch, South Africa. Electronic address:

Ethnopharmacological Relevance: Extracts from and alkaloids contained in plants in the genus Sceletium have been reported to inhibit ligand binding to serotonin transporter. From this, the conclusion was made that Sceletium products act as selective serotonin-reuptake inhibitors. However, other mechanisms which may similarly result in the anxiolytic or anti-depressant effect ascribed to Sceletium, such as monoamine release, have not been investigated.

Aims Of The Study: The current study investigated simultaneously and at two consecutive time points, the effect of high-mesembrine Sceletium extract on both monoamine release and serotonin reuptake into both human astrocytes and mouse hippocampal neurons, as well as potential inhibitory effects on relevant enzyme activities.

Materials And Methods: Human astrocytes and mouse hippocampal cells were treated with citalopram or Sceletium extract for 15 and 30min, after which protein expression levels of serotonin transporter (SERT) and vesicular monoamine transporter-2 (VAMT-2) was assessed using fluorescent immunocytochemistry and digital image analysis. Efficacy of inhibition of acetylcholinesterase (AChE) and monoamine oxidate-A (MAO-A) activity were assessed using the Ellman and Olsen methods (and appropriate controls) respectively.

Results: We report the first investigation of mechanism of action of Sceletium extract in the context of serotonin transport, release and reuptake in a cellular model. Cell viability was not affected by Sceletium treatment. High-mesembrine Sceletium extract down-regulated SERT expression similarly to citalopram. In addition, VMAT-2 was upregulated significantly in response to Sceletium treatment. The extract showed only relatively mild inhibition of AChE and MAO-A.

Conclusions: We conclude that the serotonin reuptake inhibition activity ascribed to the Sceletium plant, is a secondary function to the monoamine-releasing activity of high-mesembrine Sceletium extract (Trimesemine(TM)).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jep.2015.11.034DOI Listing
January 2016

Sutherlandia frutescens may exacerbate HIV-associated neuroinflammation.

J Negat Results Biomed 2015 Jul 18;14:14. Epub 2015 Jul 18.

Department of Physiological Sciences, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.

Background: Neuroinflammation is central to the aetiology of HIV-associated neurocognitive disorders (HAND) that are prevalent in late stage AIDS. Anti-retroviral (ARV) treatments are rolled out relatively late in the context of neuroinflammatory changes, so that their usefulness in directly preventing HAND is probably limited. It is common practice for HIV+ individuals in developing countries to make use of traditional medicines. One such medicine is Sutherlandia frutescens - commonly consumed as a water infusion. Here its efficacy as an anti-inflammatory modality in this context was investigated in an in vitro co-culture model of the blood-brain barrier (BBB).

Methods: Single cultures of human astrocytes (HA), HUVECs and primary human monocytes, as well as co-cultures (BBB), were stimulated with HIV-1 subtype B & C Tat protein and/or HL2/3 cell secretory proteins after pre-treatment with S.frutescens extract. Effects of this pre-treatment on pro-inflammatory cytokine secretion and monocyte migration across the BBB were assessed.

Results: In accordance with others, B Tat was more pro-inflammatory than C Tat, validating our model. S.frutescens decreased IL-1β secretion significantly (P < 0.0001), but exacerbated both monocyte chemoattractant protein-1 (P < 0001) - a major role player in HIV-associated neuroinflammation - and CD14+ monocyte infiltration across the BBB (P < 0.01).

Conclusions: Current data illustrates that the combined use of HL2/3 cells and the simulated BBB presents an accurate, physiologically relevant in vitro model with which to study neuroinflammation in the context of HIV/AIDS. In addition, our results caution against the use of S.frutescens as anti-inflammatory modality at any stage post-HIV infection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12952-015-0031-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4506629PMC
July 2015

Exercise and inflammation-related epigenetic modifications: focus on DNA methylation.

Exerc Immunol Rev 2015 ;21:26-41

Department of Physiological Sciences, Stellenbosch University, South Africa.

Epigenetics is the study of mitotically or meiotically heritable phenotypes that occur as a result of modifications to DNA, thereby regulating gene expression independently of changes in base sequence due to manipulation of the chromatin structure. These modifications occur through a variety of mechanisms, such as DNA methylation, post-translational histone modifications, and non-coding RNAs, and can cause transcriptional suppression or activation depending on the location within the gene. Environmental stimuli, such as diet and exercise, are thought to be able to regulate these mechanisms, with inflammation as a probable contributory factor. Research into these areas is still in its infancy however. This review will focus on DNA methylation in the context of inflammation (both pro- and anti-inflammatory processes) and exercise. The complexity and relative shortcomings of some existing techniques for studying epigenetics will be highlighted, and recommendations for future study approaches made.
View Article and Find Full Text PDF

Download full-text PDF

Source
April 2015

Chronic Prosopis glandulosa treatment blunts neutrophil infiltration and enhances muscle repair after contusion injury.

Nutrients 2015 Jan 23;7(2):815-30. Epub 2015 Jan 23.

Department of Biomedical Sciences, Faculty of Health Science, Stellenbosch University, Tygerberg 7505, South Africa.

The current treatment options for soft tissue injuries remain suboptimal and often result in delayed/incomplete recovery of damaged muscle. The current study aimed to evaluate the effects of oral Prosopis glandulosa treatment on inflammation and regeneration in skeletal muscle after contusion injury, in comparison to a conventional treatment. The gastrocnemius muscle of rats was subjected to mass-drop injury and muscle samples collected after 1-, 3 h, 1- and 7 days post-injury. Rats were treated with P. glandulosa (100 mg/kg/day) either for 8 weeks prior to injury (up until day 7 post-injury), only post-injury, or with topically applied diclofenac post-injury (0.57 mg/kg). Neutrophil (His48-positive) and macrophage (F4/80-positive) infiltration was assessed by means of immunohistochemistry. Indicators of muscle satellite cell proliferation (ADAM12) and regeneration (desmin) were used to evaluate muscle repair. Chronic P. glandulosa and diclofenac treatment (p<0.0001) was associated with suppression of the neutrophil response to contusion injury, however only chronic P. glandulosa treatment facilitated more effective muscle recovery (increased ADAM12 (p<0.05) and desmin (p<0.001) expression), while diclofenac treatment had inhibitory effects on repair, despite effective inhibition of neutrophil response. Data indicates that P. glandulosa treatment results in more effective muscle repair after contusion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/nu7020815DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4344562PMC
January 2015

Inhibition of corticosteroid-binding globulin gene expression by glucocorticoids involves C/EBPβ.

PLoS One 2014 21;9(10):e110702. Epub 2014 Oct 21.

Department of Biochemistry, Stellenbosch University, Matieland, Western Cape, South Africa.

Corticosteroid-binding globulin (CBG), a negative acute phase protein produced primarily in the liver, is responsible for the transport of glucocorticoids (GCs). It also modulates the bioavailability of GCs, as only free or unbound steroids are biologically active. Fluctuations in CBG levels therefore can directly affect GC bioavailability. This study investigates the molecular mechanism whereby GCs inhibit the expression of CBG. GCs regulate gene expression via the glucocorticoid receptor (GR), which either directly binds to DNA or acts indirectly via tethering to other DNA-bound transcription factors. Although no GC-response elements (GRE) are present in the Cbg promoter, putative binding sites for C/EBPβ, able to tether to the GR, as well as HNF3α involved in GR signaling, are present. C/EBPβ, but not HNF3α, was identified as an important mediator of DEX-mediated inhibition of Cbg promoter activity by using specific deletion and mutant promoter reporter constructs of Cbg. Furthermore, knockdown of C/EBPβ protein expression reduced DEX-induced repression of CBG mRNA, confirming C/EBPβ's involvement in GC-mediated CBG repression. Chromatin immunoprecipitation (ChIP) after DEX treatment indicated increased co-recruitment of C/EBPβ and GR to the Cbg promoter, while C/EBPβ knockdown prevented GR recruitment. Together, the results suggest that DEX repression of CBG involves tethering of the GR to C/EBPβ.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0110702PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4205011PMC
December 2015

Hoodia gordonii extract targets both adipose and muscle tissue to achieve weight loss in rats.

J Ethnopharmacol 2014 Sep 24;155(2):1284-90. Epub 2014 Jul 24.

Department of Physiological Sciences, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch 7602, South Africa.

Ethnopharmacological Relevance: Hoodia gordonii (Masson) Sweet ex Decne (family Apocynaceae) is consumed globally as a natural appetite suppressant. While this effect-and its subsequent effect of weight loss-has been reported in the scientific literature, no information is available on the specific tissue types affected that accounts for the significant weight loss reported after consumption of the plant. Furthermore, most studies are performed on lean animals, so that the response of overweight or obese individuals to this plant supplement remains largely unknown.

Materials And Methods: Twelve lean and twelve obese male Wistar rats were supplemented with different doses of Hoodia gordonii extract (80 or 160 mg/kg body mass twice daily) in a placebo-controlled study, for a period of 14 days.

Results: All supplemented rats exhibited significant weight loss (P<0.001). This could be ascribed to decrease in both adipose cell size and skeletal muscle fibre size.

Conclusions: We conclude that the weight loss seen after consumption of Hoodia gordonii is due to loss of both adipose and muscle mass.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jep.2014.07.018DOI Listing
September 2014